Are two filters better than one?

[poolboyforjenny]

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

[Poconos]

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)

[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

[waterbear]

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

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.

[KesLongwood]

ok, I've noticed that the all around answer to this topic hasn't been answered, atleast not that I have seen . 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.

[duraleigh]

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.

[waterbear]

ok, I've noticed that the all around answer to this topic hasn't been answered, atleast not that I have seen . 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.

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)

[poolboyforjenny]

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

[Poconos]

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

[duraleigh]

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.