Are two filters better than one?

I've had my pool for about a year. It's an above ground, 11.5k gallons, with a sand filter. This forum helped me get the algae cleaned up but now i have a different problem. Where i live there is a lot of fine dust. This dust settles to the bottom of the pool and if it is stirred up it creates a cloudy pool. Apparently my sand filter can't clean the water even when i vacuum to the filter. The vacuum picks it up but you see a cloud coming out of the return line into the pool. Yes i could vacuum to waste but then i'd be filling my pool every other day. My question is---Is it possible to install a cartridge filter inline with my sand filter? This would let the sand filter pick up the larger particles(bugs, grass, etc) and let the cartridge pick up the dust. I don't know if it would be worth using two or just replacing my sand with a cartridge filter. I would like to use a DE but i don't want to back wash into my back yard and just have powder all over the ground.

Do I need to just switch over to a new type of filter? Do i have something wrong with my sand filter? Do they make a 5 micron pool filter to put in line with my sand filter? Hope someone can help.

thanks
tc

Welcome to the forum.
I actually thought about two series filters years ago for the exact same problem of fine dust. Silt from my stream I use for fill water. Wound up throwing some DE in the sand filter and that works great. Can't imagine the little bit of DE would harm anything in your yard. This info was posted on the old forum before the crash. On a 300# Hayward sand filter about 2 cups of DE raises the nominal pressure about 1 psi. Trick is to calibrate the system. For the first couple times add a little DE and wait 15 minutes or so for the pressure to stabilize. I found it takes a little time for the pressure to stabilize. Keep adding in small increments until you get about a 1 psi increase. Once you are calibrated you can dump the right amount of DE in at once. I mix it with water in a 5 gal pail before dumping in the skimmer. Of course once you get rid of the fine stuff you can revert to the plain old sand filter mode. Two filters would work too but I'd plumb in a way to bypass the cartridge.
Hope this helps.
Al
(ajs-1)

Heres your two options that I know Of.

1. replace your sand with Zeobrite. Filters down to 1 Micron

2. Kind of a stupid looking product but it does work "Slime Bag"

http://www.cleanerpools.net/

Good luck

If adding DE to a sand filter, how long should it stay in there? Just til the next backwash is needed? How soon can I start vacuuming to the filter after adding DE to the sand filter?

Right now my filter just blows all the silt back into the pool thru the return line, does this mean that the silt is too fine or that there's something really wrong with the filter. Just curious so that i don't dump DE straight into the pool.

Thanks in advance.

tc

If you can see stuff coming out the return jets my guess is there is something wrong with the filter. On the other questions, I usually wait 20 minutes or so after adding DE before I vacuum. It takes some of that time for the pressure to stabilize. I also run with DE all the time, usually. After backwashing I chuck in more DE. Something you can try, when you add DE see if the white stuff comes out the returns. Try a cup or so...won't hurt anything. If it does then the filter has a problem. Could be a broken lateral at the bottom of the sand bed. I see in your profile you're in North Texas. Don't know the Texas Winters but could you have freeze damage? I doubt it. Also, when vacuuming settled silt I've never seen it come out the returns, even with just plain sand. It does get through but I can't see it. Best I can do for now. Keep us posted.
Al

Hi, Poolboy,

I completely agree with Al. (poconos) A correctly working sand filter should do a much better job than you're describing.

Sounds like you need to take the top off that rascal and do some inspection. A broken lateral would be the most likely culprit, I think. Let us know what you find.

Dave S.

I guess I will get to inspecting the pool sand filter next weekend. Just finished laying 14 palettes of sod. I was afraid there may be something wrong with the filter but i guess i'm trying to check everything else prior to tearing it down.

When i vacuum the silt, the water from the return is cloudy. When the filter is running (not vacuuming the bottom), the return water looks fine. Thats why i thought the silt was so fine that the sand couldn't contain it. Hopefully I will find out next weekend if i'm off. The water chemistry is good, and the water is clear, with the exception of grass clippings from mowing and the silt at the bottom.

Thanks for ya'lls help. Yes i'm from Texas.

tc

I have somewhat the same problem...there is a lot of "dust" in the air by my pool...trees collect it, wind blows, dust in the water! I don't see the dust/dirt returning in the return jet, though. I switched to the zeolite 2 years ago, and that really didn't help me. I'm going to try the skimmer sock this year to see if when I vacuum the dirt will be caught in it!

Good luck.

We have tons of pollen in NJ--they are saying this is the worst spring for allergies in many years. My sand filter works just fine on it.

I do use Al's DE strategy. A 10lb box should last all summer, even adding a cup each backwash.

While I don't personally use the "slime bag", it should work well. I do use skimmer socks and they pull a ton of junk out before it hits the filter.

Still, a filter problem sounds likely. Also see if you can determine if your pump is too big for the filter--that will cause problems and eventually damage the filter.

the skimmer socks work really well. our neighbors have bushes with little flowers that blow into our pool for about six weeks every year and those little socks really help catch them before getting into the filter. we just have to go out and change or clean sock a few times a day during that time. the socks pick up a lot of other fine things, too.:)

One thing you can do also, when you vacuum, set the valve to waste. You do not need to be running that sediment back through a filter that does not work right. AT least with the vacuuming to waste, you are eliminating the stuff that settles


Hal

I used the vacuum to waste method, and felt that I was really losing a lot of water. I didn't think that I could get all of the "dust" out without going below my skimmer. I usually have the water level above the skimmer opening, too!

I'm not sure what could be wrong with the filter/pump in order to check things??? Any ideas?

Quote:

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Originally Posted by poolboyforjenny

I guess I will get to inspecting the pool sand filter next weekend. Just finished laying 14 palettes of sod. I was afraid there may be something wrong with the filter but i guess i'm trying to check everything else prior to tearing it down.

When i vacuum the silt, the water from the return is cloudy. When the filter is running (not vacuuming the bottom), the return water looks fine. Thats why i thought the silt was so fine that the sand couldn't contain it. Hopefully I will find out next weekend if i'm off. The water chemistry is good, and the water is clear, with the exception of grass clippings from mowing and the silt at the bottom.

Thanks for ya'lls help. Yes i'm from Texas.

tc

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Vaccum to waste so that it doesn't come back into the pool.

ummm I was wondering how this all turned out as I have the exact same problem with silt and fine dust coming back through the return jet when I vacuum. I am troubleshooting in another area of the forum but thought a reply here might yield a response from the person who started this thread.

I have same problem, but think it's from the street that runs parallel to my pool. It's about 15' from pool and separated by an 8' wooden fence. Problem is that it's a low spot where creek run goes behind my property and then under streets. Two streets actually, since it's a divided street and speed limit is 30. I think this because it collects on the coping--above ground pool.
Anyway, I'll try the DE thing, just to get better filtration. Also wondering how poolboy was doing w/ his problem.

Quote:

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Originally Posted by InfinityPools

Heres your two options that I know Of.

1. replace your sand with Zeobrite. Filters down to 1 Micron

2. Kind of a stupid looking product but it does work "Slime Bag"

http://www.cleanerpools.net/

Good luck

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Even DE ONLY filters to abut 5 or 6 microns. The claims for zeolite are based on the 'pores' in the grains. However, the grains are about the same size as a sand grain and water is going to take the path of least resistance so most of the filtering will take place BETWEEN the grains, just like with sand. The filtering ability is only slightly better. It is good at ammonia scavaging, however, so it might help prevent the formation of CC. Zeolite is the new "craze" in the pool industry but it has been used in aquariums (primarily for it's ammonia scavaging properties and not for mechanical filtration) for many years now. As a mechanical filter is has proved to be not much better than sand. The "Slime Bag" is a micron filter bag. Once again these have been used in aquariums for quite some time now. They do work but have to be changed frequently and can create some (or quite a bit!) backpressure in a pressurized system. In aquariums micron bags are ususally used in non pressurized 'wet/dry' or sump filters with a low flow rate.

ok, I've noticed that the all around answer to this topic hasn't been answered, atleast not that I have seen :p . Does a "Duel" Filter system work or not? I.E. A Pool->Sand->Cartridge->Pool set up with a bypass between the Sand and Cartridge connection so its Pool->Sand->Pool. Right now I have a Cyclone 200 Cartrage with a 1.5 HP Dual Speed Pump (and to me, its a *****). I have been thinking about getting a BaquaPure 2600 Sand Filter System and start using Baquacil.

Keslongwood,

The answer seems pretty clear to me. Two filters ARE better than one. In fact, three filters are better than two. Come to think of it, four would be even better. Start with sand, then into a cartridge and then into a DE.

It can be as complex as you like but, simply, more filtration will result in cleaner water. Would I ever do it? Of course not. My pool is crystal clear with a sand filter.

As an aside, I noticed the filtration at one of those huge Ripley's aquariums is sand....I think they had three set up in series.

Now, the real point of my post. I would suggest reading on this forum the experiences people have had with baquacil. You may very well rethink baquacil as your sanitizer. I'm pretty sure others will opine soon....even tho we're sorta' hijacking the thread.

Using Baquacil is still in the air, I am however trying to get the filter for it, BaquaPure 2600 Sand Filter. Its basicly just like every other sand filter, cept its blue, and I like blue ^ ^. I did to a thread asking on where I can find one.

Quote:

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Originally Posted by KesLongwood

Using Baquacil is still in the air, I am however trying to get the filter for it, BaquaPure 2600 Sand Filter. Its basicly just like every other sand filter, cept its blue, and I like blue ^ ^. I did to a thread asking on where I can find one.

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Are you serious?! OMFG

Quote:

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Originally Posted by KesLongwood

ok, I've noticed that the all around answer to this topic hasn't been answered, atleast not that I have seen :p . Does a "Duel" Filter system work or not? I.E. A Pool->Sand->Cartridge->Pool set up with a bypass between the Sand and Cartridge connection so its Pool->Sand->Pool. Right now I have a Cyclone 200 Cartrage with a 1.5 HP Dual Speed Pump (and to me, its a *****). I have been thinking about getting a BaquaPure 2600 Sand Filter System and start using Baquacil.

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The biggest problem I see with using two filters in line would be backpressure and flow rates. Not sure what it would take to over come them but I know it can be done because many commercial pools use multiple filters (although I don't know if they are in series or parallel. It would seem that in series they would increase the backpressure and decrease the flow rate and in parallel the opposite would happen...I know this happens in aquarium filtration because I have experienced it)

I have two filters. I have A Dynaflo 1 Hp two-speed pump hooked up to a Hayward 300 lb. sand filter with 300 lbs of filter sand from Leslie's, and then it goes to a Pentair 150 cartridge filter and then to the pool. Even on low speed right back to the pool I have tremendous flow.

I have it hooked up to ten 2' x 20' solar panels on top of our two story house and on high speed it has great pressure. You can see the water current going way out toward the middle of the pool. On low speed, it does not have enough pressure to to go up two stories, but it didn't when I had it only hooked up to the cartridge filter. I leave it on low speed during the night and high speed when I am using the solar panels.

I bought the Hayward S224T used on ebay for $ 124 including freight. It looks brand new. I plumbed everything with 1 1/2" PVC. It works great.
My pool is crystal clear.

Aranon

Aranon,

Quote:

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On low speed, it does not have enough pressure to to go up two stories, but it didn't when I had it only hooked up to the cartridge filter.

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Once your system is primed, the vertical height of any part of your system, including solar panels, is irrelevant to the pump. It will circulate thru the panels just fine on low speed.

I can have the pump on high and everything is going good and I got lots of pressure and everything. The water is going up through the 1 1/2 PVC to the second story flat roof and I got warm water returning, but when I switch the pump to low speed nothing changes for about a min or so and then the water stops flowing. I waited for about five min to see what would happen and nothing. Everything is running, but no water is returning back to my pool.

I switch back to high speed and in about 30 seconds the water comes back on. Tried this several times and same effect every time. My only conclusion is that on low speed the pump does not have enough power to push the water up that high and through 10 solar panels. If you got any solutions, I am up for them. When I had the solar panels on the ground just trying them out it worked on low speed and the water seemed to come out hotter.

I keep wrestling in my mind would it be better to have low speed and hotter water but less flow, or high speed with warm water but more flow. On one had I look at this that yeah, the water is hotter at low speed but I am not putting much water in the pool at a time so it is not really doing much. ( Its a big pool, 18' x 40' oval by 54" high) On the other hand I am adding large volumes of water at higher pressure that is putting in a little cooler water but lots of it and shooting it out really far toward the middle. My thinking is that the water turnover rate is going to be greater at high speed and should bring the temperature up quicker at higher volume and pressure than hotter water at low pressure, and low volume. Sort of like which is going to heat you bath tub up quicker if you start with a tub full of cold water, a small trickle of hot water coming in at 100 degrees or a large full blast volume of 90 degree water. The difference between the low speed (when it was working on the ground was 10 to 11 degrees difference) Right now my water at high speed is coming out at around 90-92 degrees from the solar panels.

Pleased advise how the pump should operate fine on low speed going up 2 stories. From what I gather low speed is 1/3 hp and high speed is 1 hp.

Thanks
Aranon

Hi, Aranon,

First off, I'm not sure there is any advantage in operating the panels at low speed. I think you would have to do some engineering calculations to decide how you get the most bang for your buck. My thought would be that on a really solar intense day, hi speed would be best and then, maybe on a cloudy to partly cloudy day it may be more efficient on low. That would be noticeably above my ability to calculate that but the slide rule dudes can do it.

Now, to your question. The short answer is that no matter how high the column of water is, the energy required to push up that water is equally offset by the column of water pulling down and returning to the pool on the outflow. In essence, you work against gravity going up but then gravity returns the favor by pulling down with an equal force on the descending water. That said, there can be virtually no air in the lines for that to work.

As to why that will not work for you I'm not sure. There is, of course, a little more friction from the increased length of PVC pipe (and, possibly lack of capacity) but the end result would only be a diminished but stable flow. Perhaps others will see this post and have experienced the same problem.

Thats exactly what I thought. If I could get the water up and back down then it shouldn't take much to keep it going since the water going down should act like some sort of siphon effect pulling the water down and to a small part up too. But that does not seem to be the case. The strange part is that I have great pressure for about a min to a min and a half after I switch the pump to low speed and then it slows down to nothing. I don't know whats going on. Got the pool up to 85 degrees. All we want it up to is 88 degrees so I don't think we are going to have a problem, but it's got me stumped. I have read on other post that low speed pumps will not carry the water up to the roof and I am going up two stories. Any help would be greatly appreciated. Thanks.
Aranon

Aranon,

You might send a PM to mas985. He is excellent at calculating Total Dynamic Head and it IS possible that those ten solar panels offer so much resistance that your pump can't overcome it on low. If that's the case, you would have the same result if the panels were at pool level or even in the basement.

The panels worked fine on the ground at low speed

We have completely hi-jacked tc's thread. Sorry.

Sorry about the High-Jack TC.
Aranon