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.:)