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Domestic pool turnover rates
Quote:
Originally Posted by
mas985
First the whole concept of turnover for residential pools is flawed (see pump run time study in my sig). There is no minimum turnover required for a residential pool so minimum flow rates are really only important for things such as heaters and SWGs and SPAs so you really don't need to bother trying to figure it out unless you have one of these features.
No need to. A pool can get by with as little as 2 hours of run time (see study).
I couldn't agree more Mark,
The chlorine kills what it can in under a minute, what isn't killed by chlorine has to be filtered out. How quickly should this be filtered out? should it be a hour or 8 hours? If the filtration isn't good enough then the whole lot is just recirculated so you spend on electricity achieving very little.
The only thing I couldn't see in your pump run time study is a turbidity measure of how clear the water was. It seemed to me it was just an observation?
I filter my water 24/7 using my energy efficient system, this achieves a better result than a short pump run time for several reasons.
1. The dirt and debris actually go into the skimmers because the system is running so a lot less makes it to the bottom which is what happens when a system is off.
2. This slower rate filtration improves the filtration process by a factor of 4 so catching much finer particles ie it actually removes the fine stuff and improves the turbidity. Conventionally this was 5NTU now 0.5-1 NTU.
3. The power consumed by a conventional system in 2 hours of running is sufficient to run my pool for 24 hours.
Why did turnover rates ever become popular as they tend to be the focus rather than the really clean clear water achieved by proper filtration which begins when you half the hourly flow rate figure written by the manufacturers on their filter information.
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Re: Domestic pool turnover rates
Quote:
Originally Posted by
Teapot
The chlorine kills what it can in under a minute, what isn't killed by chlorine has to be filtered out. How quickly should this be filtered out? should it be a hour or 8 hours? If the filtration isn't good enough then the whole lot is just recirculated so you spend on electricity achieving very little.
I am not sure what you meant by this but you really shouldn't try to filter out live bacteria or live algae or it will clog the filter. The only thing that should be filtered out of a pool are dead organics and debris.
As for turbidity, I run for only 2-4 hours per day and have never had any signs of turbidity. I don't think it is a real issue for most pools.
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Re: Domestic pool turnover rates
Quote:
Originally Posted by
mas985
As for turbidity, I run for only 2-4 hours per day and have never had any signs of turbidity. I don't think it is a real issue for most pools.
What considerations would increase that run time? We have debris from out arbor vitae trees falling into the pool all the time, and we can't be out there manually skimming all the time. Would just 2-4 hours per day on high be enough and then a good chunk more on low be OK?
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Re: Domestic pool turnover rates
Quote:
Originally Posted by
mas985
I am not sure what you meant by this but you really shouldn't try to filter out live bacteria or live algae or it will clog the filter. The only thing that should be filtered out of a pool are dead organics and debris.
As for turbidity, I run for only 2-4 hours per day and have never had any signs of turbidity. I don't think it is a real issue for most pools.
As I said chlorine will kill what in can in under a minute, that would be lots of different bacteria, virus's etc including algae spores so that's the job done except for chlorine resistant types, like Giardia and Cryptosporidium and oocysts which need filtering out (this depends on the filtration being good enough and may also need flocculent. Generally the pumps are too big and the filters too small to achieve great filtration, eyesight is too bad to judge.
If you filter for 2-4 hours only and that is sufficient it may of course depend on where you live and your pool is situated with tree debris etc but with the water stationary for 20-22 hours of the day anything entering will become water logged and sink. This may not effect turbidity whilst no swimmers are in the pool but swimmers and quickly the water becomes cloudy. The same with vacuuming the pool the little dust cloud that gets stirred up in front of the vac head which leaves the pool slightly less clear than before you started.
If the system is running 24/7 then the detritus gets into the skimmers not to the bottom of the pool. It seems to take barely any energy to circulate the chemicals to keep it all mixed but you do need a flow across the pool of a minimum 22 gallons per minute to make the skimmers system work (for a pool of my size 24 x 12) Jets are carefully arranged to mix the water and over a period of time the water gets clearer and clearer. OK, I am no longer using sand so the filtration is far better in terms of how fine it filters which is more important as electricity should be put to good use trapping fine particles and not recirculating them which is what happends when the pump is too large for the filter.
I have run many pools the old way and then experimented and unequivocally the water is cleaner, clearer and takes less maintenance when run 24/7 and turbidity dropped from 5 NTU's (very clear) to 0.5-10 NTU's (incredibly optically clear) AS far as I can ascertain there is nothing to be gained from short pump runs where the power is equal to 24 hour running. I am not saying you can't run short times and be happy with the result but done the other way 24/7 on very low energy (around 50watts/hour in my case but that's 39 watts over night) Not everyone could do this but even a 1/8th-1/4 hp pump would be more than sufficient for most pool filtration and just keep the old pump for vacuuming and backwash. I use a pool blaster max for the occasional leaf that misses the skimmer of the bit of dirt from after the rain.
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Re: Domestic pool turnover rates
This is bad advice and not something we can endorse. The whole philosophy of OF is making things simple, inexpensive and effective. Running 24/7 unless you are fighting a bloom is wasting money. And you sound like you are arguing against vacuuming. Not going to fly here.
Self-described experts are not accepted at face-value here.
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Re: Domestic pool turnover rates
Carl, please don't take this the wrong way, it's not bad advice it's different advice. What is OF?
Making things simple, inexpensive and effective are my bywords to.
24/7 isn't wasting money when the cost is less than your pump running for two-three hours.
Not arguing at all.
Vacuuming is necessary but less so, I sold my pool robot as it was not needed the pool doesn't get that dirty any longer.
Ben is a Pioneer, this forum is great but does that mean there isn't another alternative? I have run many pools the old way and they are more work, 24/7 has a drawback to, you have to empty the skimmer baskets more frequently as that's where the debris ends up, not on the bottom.
This is new low energy running, only possible because new parts come along.
This idea is better for management and better for the environment. CO2 levels need to be reduced, according to a University calculator my pool produces 128kg of CO2 by comparison a conventional pool (3/4 hp) would produce 2 tons of CO2.
CO2 is causing the oceans to become acidic, on the present graph the fish will begin to die by 2015, if there is another way to run things shouldn't we look at it?
http://news.nationalgeographic.com/n...ic-oceans.html
http://www.awi.de/en/news/background...g_more_acidic/
"Self described experts are not accepted at face value here", no problem, I am not selling a product, no junk science gadget just a concept that I have spent a few years exploring and installing on my customers pools. People can choose their own ways I just wanted to add something to the debate.
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Re: Domestic pool turnover rates
The math doesn't add up. I run my pool at low 12hrs a day solely to keep my solar panel decking cool and the water warm. Running it 24/7 will NOT save me money, it will cost money. You are not understanding Mark's point.
Different ideas have to be proven before we allow them given as advice here. And many have been, including, for example, SWCGs, high borate levels, and TA levels below "standard range" to name a few. But they all have been proven, not merely asserted.
If you want to continue this, take it to the China Shop until you can prove it.
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Re: Domestic pool turnover rates
Carl, I do understand Mark's point. Mark has been terrifically helpful over the years with the information he has passed on to me. Without that information it would have taken a lot longer and cost a lot more in research.
I know at the moment it doesn't seem logical to you to run 24 hours a day but rather than go around in circles can we put some facts and figures down? I don't know the cost of electricity where you are so that would be useful.
How much electricity per hour do you use on low speed?
Do you know your actual flow rate on low?
What is the flow rate needed to run your heating (min flow)
If the electrical energy used for 24 hour running is less than you use for 12 hour running that would still be a saving, yes?
On a separate note: I didn't know running low TA levels was ok on the pool forum, I have been doing the same over in the UK and France as it didn't make any sense to run at a high TA (Vinyl pools only) currently run at TA 40ppm with very stable pH. I have a customer who is running around 22ppm TA as their water is really soft in that area still no bad effects and very stable pH.
If you would prefer to move the thread to the china shop I am OK with that if it's the proper place but I don't just want the topic to gather dust.
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Re: Domestic pool turnover rates
I have moved this to the China Shop.
My low speed setting runs around 1/4 hp vs the 1hp full speed. My solar panels cannot be opened more than a crack at full speed because they will distort and leak, but at low can be opened all the way.
There is no possible way running at low speed for 24 hours will NOT use double the KWH of running at low speed for 12 hours.
Personally, I see Mark's point as being what is NEEDED to distribute chems evenly and actually filter the water. It doesn't take into account ancillary needs like skimming the surface, aerating to raise pH without raising TA, sufficient run time for an SWCG, or solar panels. Nor does he claim it does. He merely claims that a full daily turnover of water isn't really necessary.
As for cost savings, usually 2speed pumps can run far longer and more efficiently. Even if we go back to the touchstone of one turnover per day, what is the point of a 24/7 run unless your pump is 'way too small for your pool? If I can turn over my water at low in 10-12 hours, why run it doubly long? If I can turn it over in 6 hours at high, I will still use double the KWH of a turnover at low. You cannot magically squeeze more electricity out of a pump by running it twice as long AT THE SAME SPEED!
TA is a buffer for pH. I cannot explain the full chemistry of Carbonic Acid and Bicarbonate ions, as I leave that to my son, the Chem major and Chem_Geek. But generally, if pH tends to trend up, keeping TA lower can slow or arrest that. Likewise if pH tends to trend down, higher TA also controls that. And, if you have a vinyl pool and your pH is stable, TA is only important if it approaches 200ppm with a CH of 400ppm or more, because you can get cloudy water and scaling.
Since I rebuilt my pool my TA has been trending high, around 170 (local water). pH has been trending down, but that's been due to two floaters filled with Tri-Chlor tabs, which are acidic, but keep FC up and add CYA. Been compensating with low doses of Borax, so pH has stayed at 7.3-7.4. But in the past, even last season, TA was at 50-60 with no problems.
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Re: Domestic pool turnover rates
Hi Carl,
Ok your running at 1/4hp, on a pool pump with plumbing and filtration load I would guestimate that is using 280 watts per hour x 12 hours = 3.36kw per day
I don't know your flow rate but again a guess at that level 38 GPM.
My system is built to be super efficient and I know if your flow rate less than 22 GPM then the skimming action on the surface is not good enough with a skimmer but it could still work with an infinity edge.
My pool runs at 23GPM overnight (16 hours) and when swimmer are in the pool 26 GPM (8 hours) but the total electricity per day is just 960 watts 0.96kw.
The reason for 24 hour running is that I have many trees and also we are in a farming area so debris is usual, if the pump isn't running this debris gets water logged and sinks, some people spend $100's on pool robots, if they spent that upgrading the system they wouldn't need the robot, I sold mine a few seasons ago. If the pump is running it gets skimmed off and the water stays cleaner.
I wish Marks report was more scientific, with proper turbidity test carried out and a particle count to see what was really in the water. If the pump is off the debris sinks but it doesn't show until it's stirred up. Since doing this the water is much clearer 0.5-1 NTU and there is no dirt or debris to stir up.
What Marks report does show is how little is really needed to keep the water in condition, too many people hung up on turnover rather than brilliant filtration which actually removes the dirt not just recirculates it.
Gage and Bidwell's paper on water turnover and dilution says after 1 turnover 63% of the water has been filtered, by my action I get a 6 hour turnover and that filters 4 times in 24 hours so 98% of the water is filtered. I am reducing the speed of my pump to just the 23 GPM for the full 24 hours as that will give just less than 3 turnover rates and 95% of the water filtered on 0.84kw of electricity and I will see if that makes any difference to the water quality. At that flow it should still be sufficient for a heat pump to run (just) but likewise a good solar setup may need a bit more push if it's not that well made but these are terrific energy savings.
There is very little leaf collecting or pool vacuuming to do compared to short running that I used to do.
Regards
John
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Re: Domestic pool turnover rates
Quote:
Originally Posted by Teapot
I wish Marks report was more scientific, with proper turbidity test carried out and a particle count to see what was really in the water. If the pump is off the debris sinks but it doesn't show until it's stirred up. Since doing this the water is much clearer 0.5-1 NTU and there is no dirt or debris to stir up.
The study seems pretty clear to me which states that they SAW no observable difference in water quality after 2 hours. If the debris sinks, then a vacuum can easily remove it without "stirring it up". The only time I have heard of someone having an issue like you are describing is when they just killed a bunch of algae and it sunk to the bottom. That debris is very light weight and can be stirred up easily but when cleaning up algae after it is killed, you should be running 24x7 anyway. But that should not happen very often if you follow the methods taught here.
Quote:
Originally Posted by Teapot
As I said chlorine will kill what in can in under a minute, that would be lots of different bacteria, virus's etc including algae spores so that's the job done except for chlorine resistant types, like Giardia and Cryptosporidium and oocysts which need filtering out (this depends on the filtration being good enough and may also need flocculent. Generally the pumps are too big and the filters too small to achieve great filtration, eyesight is too bad to judge.
Why only a minute? Chlorine does not stop killing after one minute, it should continue killing these things if the level is set properly.
Quote:
Originally Posted by Teapot
Gage and Bidwell's paper on water turnover and dilution says after 1 turnover 63% of the water has been filtered, by my action I get a 6 hour turnover and that filters 4 times in 24 hours so 98% of the water is filtered.
So what? Again, there is no good reason to filter the water at any specific turnover rate. It just doesn't matter to sanitation. Aesthetics, perhaps but only to some.
Quote:
Originally Posted by mitchryan912
What considerations would increase that run time? We have debris from out arbor vitae trees falling into the pool all the time, and we can't be out there manually skimming all the time. Would just 2-4 hours per day on high be enough and then a good chunk more on low be OK?
Removing floating debris and debris that has sunk to the bottom of the pool is entirely up to you. It is only based on your personal preference.
Some people like me could care less if there is a little debris in the bottom of the pool or even on the surface. My priority is to minimize run time.
Other people are quite anal about a pristine pool and thus require lots of run time so every spec of dirt and debris are immediately removed from the pool. However, this desire sometimes comes at a large cost.
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Re: Domestic pool turnover rates
I, for one, like a pristine pool. See above ^^^ :)
But as I pointed out that is NOT Mark's point. My reasons for running longer than is necessary for sanitation are valid, but not relevant to his point. They are separate issues.
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Re: Domestic pool turnover rates
Quote:
Originally Posted by
mas985
The study seems pretty clear to me which states that they SAW no observable difference in water quality after 2 hours. If the debris sinks, then a vacuum can easily remove it without "stirring it up". The only time I have heard of someone having an issue like you are describing is when they just killed a bunch of algae and it sunk to the bottom. That debris is very light weight and can be stirred up easily but when cleaning up algae after it is killed, you should be running 24x7 anyway.
Yes but the human eye can't see very much, if anything smaller than 30 microns. You cant see electricity so is that safe then? Although thankfully rare chlorine resistant strains of bacteria do happen so filtering them out is necessary and if you filter at that level very little chlorine or chlorine reactions are needed to keep the pool in top condition. If what I wrote was more expensive than normal I could understand the objection but I achieve these results on a lot less, call it a bonus.
Why only a minute? Chlorine does not stop killing after one minute, it should continue killing these things if the level is set properly.
Now that is a miss understanding, chlorine doesn't stop killing of course but it can terminate most common bacteria and virus etc in under a minute. That's why when the level of chlorine present is sufficient then high filtration rates are not needed as the report also showed. In fact because most people have pumps to big for there filters they are wasting more electricity breaking up whats filtered into smaller parts that just pass through the filter.
So what? Again, there is no good reason to filter the water at any specific turnover rate. It just doesn't matter to sanitation. Aesthetics, perhaps but only to some.
Yes agreed, I just made observations about the rate Not a recommendation.
Removing floating debris and debris that has sunk to the bottom of the pool is entirely up to you. It is only based on your personal preference.
Some people like me could care less if there is a little debris in the bottom of the pool or even on the surface. My priority is to minimize run time.
My priority is to minimise electricity bills, and cleaning all the other parts come as a bonus. My pool is let to paying guests they can be quite anal.
Other people are quite anal about a pristine pool and thus require lots of run time so every spec of dirt and debris are immediately removed from the pool. However, this desire sometimes comes at a large cost.
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Re: Domestic pool turnover rates
Teapot:
Are you a commercial pool operator? "My pool is let to paying guests..." makes me infer that you are.
Anyone in the pool business is required to very specifically state that in their signature. If you are in the business of SELLING "Passivpool" then you must explicitly say so. If you are not and are merely singing its praises in your sig, that's OK.
But again, if you are a commercial pool operator or in the pool biz you must say so--and abide by our AUP for pool pros.
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Re: Domestic pool turnover rates
Quote:
Originally Posted by
Teapot
The chlorine kills what it can in under a minute, what isn't killed by chlorine has to be filtered out. How quickly should this be filtered out? should it be a hour or 8 hours? If the filtration isn't good enough then the whole lot is just recirculated so you spend on electricity achieving very little.
:
1. The dirt and debris actually go into the skimmers because the system is running so a lot less makes it to the bottom which is what happens when a system is off.
Quote:
Originally Posted by
Teapot
As I said chlorine will kill what in can in under a minute, that would be lots of different bacteria, virus's etc including algae spores so that's the job done except for chlorine resistant types, like Giardia and Cryptosporidium and oocysts which need filtering out (this depends on the filtration being good enough and may also need flocculent. Generally the pumps are too big and the filters too small to achieve great filtration, eyesight is too bad to judge.
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If the system is running 24/7 then the detritus gets into the skimmers not to the bottom of the pool.
You don't filter out pathogens. Bacteria and viruses are to be killed by chlorine in the bulk pool water to prevent person-to-person transmission. It's only the protozoan oocysts that take a lot longer, especially for Cryptosporidium parvum that for practical purposes isn't killed by chlorine (at normal levels), but that is very uncommon in residential pools. Those Crypto spores are also too small to get caught in sand or even most cartridge filters without coagulants. In the U.S., the CDC Model Aquatic Health Code (MAHC) proposal requires the use of supplemental systems such as ozone or UV in the circulation system to kill Crypto in high-risk venues. There are some other unusual pathogens that aren't killed readily by chlorine such as iron bacteria and of course if one isn't diligent about maintaining the proper FC/CYA level then biofilms can form and be more difficult to remove.
If you are running on low speed, then unless you have an outstanding circulation system with many returns, you won't get great skimmer action. At low flow rates one simply doesn't have enough water flow to move leaves around the pool and into the skimmer quickly enough. This depends, of course, on pool design. Some pools will work OK at low speeds, but many won't since they were designed originally for high speed pumps so the placement and number of returns is pretty paltry when run at low speeds.
I agree with you though that if you don't run during some times throughout the day (not necessarily 24 hours, but on and off so the "off times" aren't too long, then that will help prevent surface debris from getting water logged and sinking. Of course, with a pool sweep such items can get collected from the bottom so I'm not sure why that's a problem. If you don't have a pool sweep, then what you propose keeping the water moving at the surface longer would make some sense, with the caveat of sufficient flow to actually move things towards and into the skimmer.
By the way, we aren't proposing to run at high speeds for long times. If a pool can run at low speeds all the time that the pump is on with reasonable skimmer action, then great. What Mark is saying is that whatever the pump speed is, it doesn't usually need to be run for as long as people think. You can run your low speed for perhaps hours over the 24 hour period and have great water clarity. If one needs some skimmer action, then perhaps one needs an hour every 8 hours at high speed for that. And so on. In other words, use the low speed whenever possible and use the shortest times to achieve the desired result. That results in the lowest energy usage to achieve the desired water clarity and skimming action.
As for low TA levels, that has been suggested for many years to have more stable pH. I don't remember when Ben suggested it but it was a long time ago. Just remember that if you have a plaster pool then you need to have a higher pH target and/or higher CH to compensate for the saturation index to saturate the water with calcium carbonate to protect the plaster.
Quote:
Originally Posted by
Teapot
Gage and Bidwell's paper on water turnover and dilution says after 1 turnover 63% of the water has been filtered, by my action I get a 6 hour turnover and that filters 4 times in 24 hours so 98% of the water is filtered.
See the section "Turnover Rate and Law of Dilution" in the first post of the thread Certified Pool Operator (CPO) training -- What is not taught. The Gage and Bidwell model does NOT tell you how much of the pool water has "seen" the filter. It is less than that because they assume a specific amount of contamination introduced once per day and then calculate the clarification percentage. He says that one turnover has only 42% clarification. Fortunately you aren't quoting that number and are instead quoting the correct 63% number, but that has nothing to do with Gage and Bidwell. So your numbers are correct, but you shouldn't refer to Gage and Bidwell since that can be confusing.
Quote:
Originally Posted by
Teapot
Yes but the human eye can't see very much, if anything smaller than 30 microns. You cant see electricity so is that safe then? Although thankfully rare chlorine resistant strains of bacteria do happen so filtering them out is necessary and if you filter at that level very little chlorine or chlorine reactions are needed to keep the pool in top condition. If what I wrote was more expensive than normal I could understand the objection but I achieve these results on a lot less, call it a bonus.
Believe me, you won't be filtering out bacteria. Most bacteria are going to attach themselves to surfaces or to particles because they generally only reproduce affixed and not when free-floating. You can't rely on filtration for most pathogens. Oocysts and spores are difference since they generally don't attach and instead float through the water so will generally get circulated. Though the same is also true for viruses, filters won't capture them (without coagulation).
Mark has always said that using low-speed (or the lower speeds of variable speed) pumps saves a lot of energy and you agree with that. So the only question left is how long to run at this lower speed. This is where you two differ, but I think would agree that you need to run at higher speed part of the time if that is necessary to achieve a specific goal such as getting proper skimmer action and that clearly depends a lot on specific pool design.
Then the question becomes how to space out this higher speed over the day and how long to run at low speed and how to space that out. Here is where you differ where Mark is saying you don't need even a full turnover in most residential pools whereas you are going for 24/7 filtration and have more turnovers. That obviously uses more energy than if you cut back your total runtime, even if you spaced it so that you didn't have long "off" periods to still achieve your goal of having mostly skimmer action rather than picking up debris in a pool sweep.
My pool runs for roughly one turnover per day but not because of any filtration need but rather because my solar system runs at 48 GPM and is on longer, usually 4-6 hours per day depending on the time of year. The pump is on low speed with 26 GPM for the other 2-4 hours for a total of 8. With my 16,000 gallon pool this translates into 1.11 to 1.275 turnovers. My pool looks like the following:
http://richardfalk.home.comcast.net/...ol/PoolDay.jpg
http://richardfalk.home.comcast.net/.../PoolNight.jpg
and a photo of one of my main drains at night is the following:
http://richardfalk.home.comcast.net/.../PoolDrain.jpg
Since I only have a cartridge filter, I'm sure I could get even better water clarity but it's plenty fine for me as it is. The only thing that might improve from even longer circulation is reducing the number of floaties one sees in the pool light assuming that such floaties aren't just in a "dead" pattern going around the pool (i.e. a bad circulation pattern that extra circulation time won't fix). I have a pool cover that keeps the pool relatively free of debris though it is used nearly every day so during that time stuff does get blown in. I do clear the skimmer basket, pool sweep bag, and pump basket of debris at least weekly (skimmer basket sometimes more frequently, especially during fall).
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Re: Domestic pool turnover rates
Quote:
Originally Posted by
CarlD
Teapot:
Are you a commercial pool operator? "My pool is let to paying guests..." makes me infer that you are.
Anyone in the pool business is required to very specifically state that in their signature. If you are in the business of SELLING "Passivpool" then you must explicitly say so. If you are not and are merely singing its praises in your sig, that's OK.
But again, if you are a commercial pool operator or in the pool biz you must say so--and abide by our AUP for pool pros.
Hi Carl,
No I am not a commercial pool operator, I have a holiday home which guest can use. When I joined, Ben and I discussed this and he looked at my place. I also made it known to Ben that I do work in the pool industry but no mention was made of needing to do anything else but he warned me not to sell and I am not. I am sharing information. I am however shocked that you have handed out warnings which to me, seem to be for actually having an opinion and sharing it.
Ben had an opinion, he started this forum because his opinion was different to others, some have copied his idea and run off with it.
Mark's information has always been helpful, I am not crossing that line and as you wished the topic is now in the China Shop although saving energy is main stream and every one want's to save money, that's why they are on here and not down the pool store?
I would prefer it if you feel I have broken a rule to point that out without administering a warning, maybe an email?
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Re: Domestic pool turnover rates
Thank you Richard,
Yes whilst I do run 24/7 it's due to having lots of trees around, not everyone will, but some who post on the forum do so different ways of running for given situations. I am not saying everyone has to run 24 hours and if you are willing to accept less, fine but has anyone explored what happens if you do run 24 hours, no because of the cost. My cost are low, very low, It cost me less to run 24 hours than most other pools cost for 2 hours. That's where the study has been going on.
Just like Mark's study on turnover it appears we need a lot less turnover than previously thought. If I had less trees I would almost certainly reduce the run time but as I said you can only skim the surface if the equipment is running.
Yes I appreciate what can and cannot be filtered but even biofilms break free and normal filtration doesn't catch them it circulates them.
There is as you point out a point at which the water flow is insufficient to achieve a skimming action and so there is a flow at which we can't go any lower in my pool that appears to be 23GPM. Being an oval pool it's more hydrodynamic than a rectangle and you hit the spot with the return jets. Too many lazy pool builders do not know or plan the placement of skimmers or returns or even the number of returns. I was able to sell my robot as running as I do it wasn't needed even with the number of trees I have but I have to empty the skimmers more frequently because that's where it all ends up and on low energy pumping the flow can drop and the automatic sensor will cut off the pump if water stops flowing to protect the pump. As you said pool equipment was never made with efficiency in mind.
Your pool looks good Richard but there is extra electricity being used for the booster pump for the pressure side cleaner, I just use a Pool Blaster max now days although I can of course use the old vacuum head and hose should anything happen but it hasn't and less work is required now to look after the pool.
Just sharing what I have spent my time doing, and the turnover thing for domestic pools is a red herring but better to have a finer filtration and collect stuff which works even better on slow filtration than fast. We are all energy savers but single speed pump pool owners may hopefully gain something.
Regards to all on the Pool Forum in case Carl doesn't like what I have written and issues a 3rd warning.
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Re: Domestic pool turnover rates
Ben is not here to make judgements or correct errors I may make as a moderator. There are only myself and WaterMom. We have to make decisions about appropriate posts ourself, without Ben.
If you have an understanding with Ben, that's fine, but your posts made it sound like you are a pro in the business--and we have definite rules about that. As I said, if you are not a pro, those rules don't apply.
I'm not sure I have access to your eMail--Ben keeps many powers to himself as is his right--and private messaging is shut down. But I do have other powers to ensure our rules are followed and decorum is maintained. I'd prefer not to use them, and rarely have over the years.
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Re: Domestic pool turnover rates
Understood Carl, Please point me to your rules for people in the industry. I am in the industry as I told Ben, if there is something I should do, add to my signature etc, please let me know but I am NOT selling anything. If you need to email me for any reason it's john@le-pre.co.uk
Hope we can continue.
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Re: Domestic pool turnover rates
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Re: Domestic pool turnover rates
Would you believe I don't have access to that?
Teapot, you do not have permission to access this page. This could be due to one of several reasons:
1. Your user account may not have sufficient privileges to access this page. Are you trying to edit someone else's post, access administrative features or some other privileged system?
2. If you are trying to post, the administrator may have disabled your account, or it may be awaiting activation.
Quote:
Originally Posted by
CarlD
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Re: Domestic pool turnover rates
Whoa! I don't get that! And I cannot change it.
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updated May 2012
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Re: Domestic pool turnover rates
Yep I remember a couple of paragraphs when I was emailed by Ben, especially "don't sell or promote stuff" I thought I was already in the special pool section as Ben or a Mod had to approve my first posts. If you need/want me to add something to make it clear to my signature etc please say so or can you carry that out? Just trying to be straight.
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Re: Domestic pool turnover rates
Quote:
Originally Posted by
Teapot
Your pool looks good Richard but there is extra electricity being used for the booster pump for the pressure side cleaner, I just use a Pool Blaster max now days although I can of course use the old vacuum head and hose should anything happen but it hasn't and less work is required now to look after the pool.
Richard uses ThePoolCleaner (I do too) which does not require a booster.
Quote:
Just like Mark's study on turnover it appears we need a lot less turnover than previously thought. If I had less trees I would almost certainly reduce the run time but as I said you can only skim the surface if the equipment is running.
It was actually Ben who found the study.
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Re: Domestic pool turnover rates
Apologies Mark & Richard I thought that was a Polaris, That model of cleaner hasn't made to the UK or Europe as far as I know. How do you rate it?
Ben, Legend!
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Re: Domestic pool turnover rates
I switched to 4-wheel pressure The Pool Cleaner when I switched to a Pentair Intelliflo VF pump. Prior to that I had a single-speed pump and a separate booster pump for a Letro Legend pool cleaner. I'm very happy with The Pool Cleaner, but I have a cover on the pool most of the time so don't get a lot of debris. I clean out the cleaner bag no more than once a week and can usually go longer between emptying the bag. When the cleaner is on, it's at 15 GPM, 2180 RPM, 540 Watts for 2 hours each night (I have a Jandy valve that switches the main pump to a dedicated line for the cleaner). I don't need to run it that often, but I never know which day is going to get the debris and my wife swims nearly every day and doesn't want debris in the pool. When the solar is on at 48 GPM that's 1500 Watts and when it is off at 26 GPM it's 300 Watts.
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Re: Domestic pool turnover rates
Richard,
I've read your posts with interest (as I almost always do). I'm baffled by one thing: Why do your solar panels require so much pressure? While I've long been an advocated of "More Flow = More Heat Energy", it seems awfully high and from what I've seen of solar panels, they are prone to leaking when the pressure is too high--I run mine on low speed all the time. When I bump the pump to high, I either turn off the panels, or shut their valves down to a crack, a trickle, to prevent them leaking. Of course FantaSea panels, nifty as they are, are far more fragile than the flexible roll-up types. I'm always checking for and repairing leaks.
As for the lower TA: I'm pretty sure it wasn't Ben who first put the concept forward. I thought it was one of the pool pros--or you--who suggested it (guess it wasn't you). Of course, in practice many of us have found it to be VERY effective to countering rising pH. Rising pH seems more mysterious than falling pH, which is almost always easy to trace, usually to Tri-Chlor or even Di-Chlor. Only with new or newly resurfaced hard (concrete/plaster) sided pools is rising pH expected.
But rising pH can be, as you know, an adverse effect of an SWCG. Many people complain about it. Yet I don't seem to have that problem and haven't in the 3 seasons I've had the SWCG. In fact, my pH has been pretty constant since I re-opened (and the Tri-Chlor tabs ran out) at 7.5-7.6 Yet my TA is around 170 due to the local water. Since pH IS stable, it ain't broke, so I'm not fixin' it!
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Re: Domestic pool turnover rates
Not to answer for CG but for solar panels on a roof with a VRV installed on the roof, you must have positive pressure at the VRV to keep it closed. Pressure drops with elevation so on a two story roof, you must have at least 11-15 PSI on the filter in order for the VRV to remain closed. A one story is better at 5-7 PSI filter pressure.
Carl, if I remember correctly, I believe your panels are in your deck so you can easily run on low speed to run the panels.
Lowering of the VRV would also allow someone to run at low speed on a two story roof but you still need to prime the panels on high speed so the controller must support that.
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Re: Domestic pool turnover rates
Thanks, Mark. Yes, it's correct that my solar panels are part of my deck and priming them is only an issue in the spring because they were drained for the winter. Other panels I've used have also not been elevated so I've no experience with the control valves needed.
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Re: Domestic pool turnover rates
The recommended flow rate for my solar panels is 4 GPM per panel and I have 12 panels in parallel so that's 48 GPM. I could run slower with somewhat less efficiency. Even going from 4 GPM per panel to 3 GPM per panel (which is the "minimum recommended") only drops efficiency from 80% to 70% while energy usage would drop from 1500 Watts down to less than 900 Watts. Or I could split the difference and do 3.5 GPM per panel at less than 1200 Watts. I've considered doing that, but haven't changed to it yet. My wife often swims earlier in the day so needs the heating to occur more quickly, but it's a dance for how high to get the temperature the night before so that it is warm enough at the start of the next day.
The other reason my pump energy cost is pretty high when solar is running is that I have a long 75 foot pipe run to and then from the solar system on the single-story roof. I lose 1.2 PSI because my PB used 2" pipe instead of 2.5" (or 3") plus the 12 panels are spread over 3 different roof hips over the length of the house. Also, marginal electricity rates are high at 35 cents per kilowatt-hour (or more). My filter pressure with solar at 48 GPM is roughly 24 PSI which is high (55 feet of head) where the highest point of solar on the roof is perhaps 20 feet high so the rest is largely inefficiency in the piping and outlets. I'm sure I could operate at a slower flow rate without the VRV opening since 36 GPM with solar on is roughly 16 PSI in my pool system.
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Re: Domestic pool turnover rates
Thanks for the explanation, Richard.
Do you use a solar cover at night, too, to hold in heat? I find it's critical to efficiency.
If you have an attic, have you thought of running additional plumbing through THAT to pick up more heat energy?
Luckily, since my panels are only about 3 1/2' above my pump and, at most 10' away, I don't have to deal with all those issues you do.
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Re: Domestic pool turnover rates
I have an automatic electric safety cover that is on all the time except when the pool is in use. The pool is used almost every day for about an hour or two. And yes, having a solar system without a pool cover will have less benefit. Basically, with no cover then overnight in the non-peak of the swim season I can lose 6ºF but with the thin non-insulating but opaque cover I lose 3ºF. If I had an insulating bubble-type cover, I'd lose around 1.5ºF.
The solar panels on the roof pick up the sun's energy directly so our attic is cool when they are running and is a side benefit to keeping the house cooler as well (though the attic is fairly well insulated from the house interior). It's more efficient to have the panels on the roof than it would be having them in the attic. For maximum efficiency in the attic one would want very dark roof tiles thermally connected to the attic. The fact that our synthetic shingles are gray and not black has them not absorb as much heat as the black solar panels and they do not transfer the heat as efficiently to the attic through the roofing materials. Roof attic heating is not an efficient solution unless the roof was designed specifically for that purpose -- it's not that such systems don't work, but that they aren't as efficient as panels on the roof.
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Re: Domestic pool turnover rates
Hm.....Can you find a way to velcro a solar cover to the underside of the auto safety cover?
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Re: Domestic pool turnover rates
Quote:
Originally Posted by
chem geek
I switched to 4-wheel pressure The Pool Cleaner when I switched to a Pentair Intelliflo VF pump. Prior to that I had a single-speed pump and a separate booster pump for a Letro Legend pool cleaner. I'm very happy with The Pool Cleaner, but I have a cover on the pool most of the time so don't get a lot of debris. I clean out the cleaner bag no more than once a week and can usually go longer between emptying the bag. When the cleaner is on, it's at 15 GPM, 2180 RPM, 540 Watts for 2 hours each night (I have a Jandy valve that switches the main pump to a dedicated line for the cleaner). I don't need to run it that often, but I never know which day is going to get the debris and my wife swims nearly every day and doesn't want debris in the pool. When the solar is on at 48 GPM that's 1500 Watts and when it is off at 26 GPM it's 300 Watts.
Hi Richard, just backing up on this thread. Is the 48GPM what is required by the solar for good heat transfer?
What are the gauge pressures for your flow rates?
As we have discussed before elsewhere the additional 1200 watts to run your pump for solar heating could, if put through an air source heat pump produce almost 6000 watts of heat for your pool. not sure what kind of output you get?
By way of comparison roughly 26 GPM 55 Watts 1700 RPM
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Re: Domestic pool turnover rates
I think Richard is telling us the 48gpm is required solely to get the water up to the roof. While I'm always an advocate that the more water you can push through your panels the more heat you'll get, short of forcing cavitation or leaks, you certainly don't need that just for the panels.
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Re: Domestic pool turnover rates
Maybe Carl, that's what I was waiting for clarification over. It's normally a pressure required to lift the water not necessarily a flow rate but in this case that 48 GPM maybe where the pump flow supplies sufficient pressure to reach the panels.
It takes time to transfer the solar energy into the water so to fast and the water won't absorb enough heat so the excess flow is just a waste of energy, there will be a point where to slow and the panel stays to hot so not supplying enough heat to the pool. Finding the sweet spot is the desirable point.
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Re: Domestic pool turnover rates
Quote:
Originally Posted by
Teapot
Maybe Carl, that's what I was waiting for clarification over. It's normally a pressure required to lift the water not necessarily a flow rate but in this case that 48 GPM maybe where the pump flow supplies sufficient pressure to reach the panels.
It takes time to transfer the solar energy into the water so to fast and the water won't absorb enough heat so the excess flow is just a waste of energy, there will be a point where to slow and the panel stays to hot so not supplying enough heat to the pool. Finding the sweet spot is the desirable point.
I'm sorry Teapot, but this is completely wrong and in contradiction to the laws of physics. It's a common mistake and INTUITIVELY it seems right, but, in fact, is not.
Remember: Transference of heat in or out is the same. By your logic you will cool your car's engine down FASTER by slowing down the water pump, the coolant flow, and by not going as fast through the air. Clearly, this is not true--you want to move the coolant through the system as fast as possible without cavitation or leakage in order to cool the engine down. And, the radiator fan goes ON when you slow down to keep air moving as fast as possible over the radiator fins and coils.
(Of course, if you don't want the engine to cool so much this isn't true--which is why there's a thermostat for those conditions).
What you are transferring is heat energy, not temperature. BTUs/Kcals, not degrees. In fact, the MOST efficient panels will NOT be getting much hotter than the pool water because they are transferring such a high percentage of heat to the water.
I have 30 solar panels, all 2'x4'. Originally, as built, they were all in a serial, one after another. My pool would heat up, but slowly and I had to keep the total water flow super-low so as not to cause leaks. Several years back, I re-plumbed the system so now there are two circuits of 15 panels each. I was able to increase the water flow, and I found my pool heats up about 40% faster than it did before. Greater flow=greater heat energy transfer.
Don't confuse heat energy with temperature. Would you rather have a flow of 10 gpm with water that's 5 degrees (F) warmer, or 1gpm of water that's 25 degrees warmer? Which has more BTUs?
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Re: Domestic pool turnover rates
Carl is correct. Faster flow rates are more efficient for heat transfer. The reason is actually very easy to understand. If the flow rate is slower, then the solar panels get hotter because the heat absorbed from the sun is not getting carried away as fast. In other words, the water temperature gets hotter, but that also makes the panels hotter. Hotter panels re-radiate and thermally conduct heat to the air especially when there is any wind. So the efficiency of the panels drops as the flow rate is lowered. With little to no wind, at 4 GPM per panel they are 80% efficient transferring 80% of the sun's total energy (which during peak noontime sun in the middle of summer on a clear day is 1000 Watts per square meter) to the water. At 3 GPM per panel they drop to being 75% efficient (I was wrong in what I wrote before -- I misread the graph). At 2 GPM they are 70% efficient. At 1 GPM they are about 60% efficient.
So yes, I could lower the flow rate through the panels and not lose too much heat transfer efficiency but save a reasonable amount of pump electricity energy as I noted. I don't actually have to have 48 GPM to keep the VRV open so to get to the roof. I could use a lower flow rate but haven't experimented to see how low I could go. See this post for details on GPM, RPM, PSI for my pool. My Watts are higher at roughly the same GPM and RPM as teapot because my pool plumbing and fixtures are not nearly as efficient. On the suction side, I've got two long (probably almost 100') 1.5" pipe with one going to pool drains (split near the end to two pipes to two separate drains) and one to a skimmer. On the pressure side, I've got one long (probably around 60-70') 2" pipe that splits at the pool to three 1.5" pipes for each of 3 returns.
With no solar at 26 GPM I'm at 1500 RPM and 275 Watts with around 4-5 PSI, but with solar at 48 GPM I'm at 3000 RPM and 1500 Watts with around 24 PSI. At 30 GPM for both, no solar is 6.5 PSI while solar is 14 PSI so you can see how much solar is adding in resistance with the very long pipe runs using 2" pipe and headers. If the VRV is 20 feet high then that would only need around 9 PSI or so (at the base; must be higher at the filter since pressure will drop along the pipe run) to keep the valve closed so I should be able to operate at 3 GPM per panel so 36 GPM total with 75% (instead of 80%) efficiency and with 2500 RPM, 900 Watts and 16 PSI. I could probably go even lower if I wanted to.
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Re: Domestic pool turnover rates
Hi Richard and Carl, sorry been away for a while.
Yes Carl, understand the physics and apologies for not explaining clearly what I meant although I get the feeling Richard understood.
It's tricky to use a the car engine analogy as there is far more heat available to get rid off so transference would be faster courtesy of 1500 high energy, high temperature explosions taking place every minute but the thermodynamic rules are essentially the same I believe. It's more that actual application on a swimming pool where the solar energy is considerably less as is the temperature (geographical situation may of course alter that if you are in Arizona, California or over my part of the world).
Carl you said "Would you rather have a flow of 10 gpm with water that's 5 degrees (F) warmer, or 1gpm of water that's 25 degrees warmer? Which has more BTUs".
Obviously we are looking for the maximum BTU's where possible but are those actual figures for what you receive or just a statement to explain your point?
My point is that in Richards example the flow rate is 48 GPM which maybe more efficient in terms of the energy gain from panels only (though I doubt it) but doing that costs him on the pump electricity an additional 1275 watts (equal to over 6kw via a air to water heat pump). Slowing the water flow through the panels as Richard has shown reduces the panels heat efficiency by a small amount but like wise reduces the electricity by a larger amount so the overall efficiency is greater.
Richard assuming the 100% or near as is achieved at 48 GPM on your setup then 80% at 4GPM/panel then the electrical saving by slowing down the flow would save considerably more although the panels would get a bit warmer they won't go passed the outside temperature as that would be equilibrium?
Finding via a graph the best point for low electricity usage to the pump and the best flow for the panel is really what I was driving at so the slower flow around the panels gains more heat energy is absorbed which may not be as efficient as faster but is more efficient when the pump electricity is also considered.
On the best pool setup I have done (not the cheapest in capital outlay terms) the flow rate on filtration is 52.8 US GPM on 81 watts with plumbing lengths about half of yours Richard. The owner is planning to use solar (Evacuated tubes and heat exchanger) so this will impact on the overall efficiency so your data is helpful, I would prefer him to use a heat pump as the headloss is a lot less so allowing him to keep the running cost to minimal but some data is needed to back up that discussion.
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Re: Domestic pool turnover rates
I'm sorry but this statement you made:
"It takes time to transfer the solar energy into the water so to fast and the water won't absorb enough heat so the excess flow is just a waste of energy, there will be a point where to slow and the panel stays to hot so not supplying enough heat to the pool. Finding the sweet spot is the desirable point."
is simply flat-out wrong.
However, the rest of your argument, that the wattage consumed pumping the water up to the roof-top panels may exceed the wattage used by a properly sized and programmed heat pump, is a valid question. Richard shows that he may be able optimize his heat gain vs his pumping wattage expenditure by slowing his pump or usage but that does NOT mean the panels themselves will work more efficiently.
The car model is actually a perfect example. The cooling system is virtually identical to a solar panel system except that the variables are different. The amount of heat energy generated by the engine may be no more than a large solar panel system, although the temperature is far higher, and pressurized to increase the boiling point of the coolant. Running your panels at night to cool your pool is exactly the same exercise as the car's engine so the same questions are valid.
Yeah, I pull the numbers out of my ...(hat)...as an example, no more.
So you are conflating apples and oranges. The question of how many watts do you burn for resultant BTU gains of solar panels vs a heat pump is valid. The assertion that moving the water faster through the panels loses efficiency (short of cavitation or leakage) isn't. They are differently things.
I'm in a different situation than Richard as my solar panels are less than a foot above my returns, so I don't have to expend huge amounts of pump energy fight gravity. Plus, the panels' own limiting factor on flow is simply failure from too much pressure. The noticeable gains in water temp from pushing the system are annoyingly offset by the cost and effort of repairing leaks or worse, replacing panels at about $70/each. When running my pump at full speed I must barely crack the valve for each circuit or risk leakage failure. Only at low speed can I full open the valves.