Domestic pool turnover rates

[Anonymous [GDPR] European in the UK]

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.

[mas985]

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.

[mitchryan912]

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?

[Anonymous [GDPR] European in the UK]

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.

[CarlD]

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.

[Anonymous [GDPR] European in the UK]

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.

[CarlD]

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.

[Anonymous [GDPR] European in the UK]

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.

[CarlD]

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.

[Anonymous [GDPR] European in the UK]

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