Filter delivers dirty de

[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.

[SunnyOptimism]

I know this sounds like generalizing but something has to be cracked, loose or torn in some way. Or there's an o-ring or gasket somewhere that is not sealing.

What you're describing is a transient situation where the pressure at start up is low allowing the "thing" that is not sealing to pass DE. Then, once the system pressurized and the DE re-coats everything, the "leak" is plugged. Remember that DE is just extremely fine silicate shells of dead marine algae. The DE particles can be as small as 3 micrometers in size but are typically 10-100micrometrs. This powder is so fine that even the smallest tear, crack or unsealed surface can allow it to pass.

So, sorry for being overly broad and not very helpful, but something is not sealed right. Looking at the design of this Hayward filter, I guarantee there's a well known engineering flaw in there somewhere. I have a Pentair QuadDE filter which is just a hybrid cartridge filter that uses DE. I like the design as there are only four cartridge units that need to be properly seated and sealed making it a low complexity design. Also, there's no mechanical bumping, just backwashing.

Keep posting results and I hope someone else here with a similar DE filter can chime in to help.