DE and algae flowing back into pool -- help me diagnose.

[impeller]

I'll take all the help I can get, so keep the advise coming. I'm having much better luck with the green algae this year, in part due to the fine Pool School and the Pool Calculator.

The dead algae thing really drove me crazy last year until I changed out the multi valve in favor of a simple push-pull valve (and actually got my filter to work). And your comments on the leaking air are timely...I'll be looking into that.

Maybe the backflowing water and DE from the filter was causing my multivalve gasket to wear out prematurely whereas the push-pull valve tolerates DE better...which is why I'm having better luck with it.?.?.?


So, just to confirm, if it's airtight, no water should flow back out of the filter after pump shutoff? I figured that since the filter is higher than the rest of the system, water could flow either down into the eyeball returns or back thru the pump into the skimmer and main drain (slowly, of course).

 

[duraleigh]

So, just to confirm, if it's airtight, no water should flow back out of the filter after pump shutoff? I figured that since the filter is higher than the rest of the system, water could flow either down into the eyeball returns or back thru the pump into the skimmer and main drain (slowly, of course).

There is really no force in either direction to encourage the water to move. Just by inertia, it will generally stay put. Many, many variables could cause some very, very slight movement, I suppose, but when my system is airtight (I also have a very small leak right now) the debris in the pump strainer basket is perfectly motionless.

 

[Vandergraff]

I am seeing something similar since I recently cleaned my filter. When my pump turns off at the end of the day I see a small cloud of DE come out of the main drain at the bottem of the pool. Apart from this the filter seem to be working fine with the water crystal clear. The small amounts of the DE are being picked up by the Polaris the next day.

So it sounds like I may have an air leak - correct? How would I locate it - I can also see small amounts of DE in the 'pump basket' that I haven't seen before.

 

[Rangeball]

The Pentair manual says that you will get a little. I think the whole problem is caused by poorly designed and built pool equipment for residential use. Pentair generally ranks high on this forum and with my local pool suppliers, but I think their stuff is ****.

I have run the exact same filter for 10+ years without any of the issues you are describing.