Sand Filter and fine silt

[DKick]

Hello all,
I have two sand filters attached to my 25K gallon pool. My issue is fine silt not captured by the sand filters getting back into the pool making it cloudy. Should I use Alum or a flocculant to settle this silt then vacuum to waste?

Thanks in advance to all helpful replies.

[CarlD]

Never heard of 2 sand filters. Are they in serial or parallel? How big are they? How big is the pump? If the pump is too strong for the filters it may just be blowing sand right through them.

We find though, that with properly sized sand filters, you can increase the filtration by adding a little DE powder--1/4 to 1/3 cup--just until the pressure increases by at least 1 lb but no more than 2 lb. DE is a cheap additive if you buy it in 10lb boxes and will last for several seasons--and runs $13-$15.

You can also add skimmer socks to your skimmer. Both of these can significantly improve sand filter performance. Cheaply.

But neither will work if your problem is mechanical.

[DKick]

I have 2 Sta Rite Crystal Flo sand filters 200 lbs each mounted in parallel with a Sta Rite 1 hp pump (1.25 service factor). I wanted the ease of a sand filter but improved filtration with 2 filters instead of one filter. I will try adding some DE to the skimmer to improve the filtration even more. Hopefully, this will catch the fine silt that comes back into the pool after vacuuming.

I added 4 to 5 lbs of Alum today to drop the cloudiness and it has tremendously dropped the cloudiness to the bottom of the pool. I vacuumed to waste and will do so again tomorrow if needed.