Filter delivers dirty de

[CarlD]

Pump: 65gpm with 30' of head.
Filter: 67 gpm.

So if you do NOT have at least 30' of head, your pump is probably exceeding your filter's max. In any case, IMHO, the filter is too small for the pump and you need a bigger cap filter or smaller pump.

[SunnyOptimism]

@CarlD nailed the pump/filter sizing issue. 30' of head is approximately 13psi pressure. What's your normal system pressure?

Also, I'd like to chime in on the DE issue. Your original post stated that DE was coming back through your return lines into the pool. I took a look at the filter manual and there is a built in check valve in the filter. The troubleshooting section clearly states that DE returning to the pool after pump shutdown could be a result of a bad check valve.

Have you disassembled the discharge elbow and confirmed the check valve is operable?

[SunnyOptimism]

Please IGNORE my last post!

You clearly stated that you replaced the check valve. I did not read your original carefully enough and missed that point. My apologies.

[FRANCIS]

yes - i spent 50 dollars on a check valve for nothing.

[SunnyOptimism]

So if I understand the problem correctly, you only get DE out of your returns when the pump shuts off, correct? During normal pump operation, the water coming out of the returns is clear, correct?

[FRANCIS]

Incorrect - Dirty DE enters the pool thru the return [eyeball jets] momentarily when the pump starts up after a period of downtime. When I say 'momentarily', it lasts a few seconds - enough for a big ugly plume of green to emerge. Once the DE re-coats the grid, the water runs clear. This is killing me. I can't allow the time clock to automatically start the pump. I need to do it manually so I can divert the slug of dirty water thru a drain temporarily.

[CarlD]

Unfortunately, it looks like most of our experts on plumbing and filter issues (other than sand) may have checked out for the season.