DE backflows into the pump strainer when the lid is open

[acpie360]

- This does not happen when the lid is closed.
- This didn't happen before. Last time I opened the strainer lid was about a month ago. I think I backwashed the filter but can't recall for sure.
- The DE filter is Pentair FNS PLus 60
- The backwash valve is also made by Pentair (can't find the P/N). It has the handle that goes up/down selecting between normal operation and backwash.

Where should I start the troubleshooting process? Once the DE gets into the strainer, it eventually drains out of bottom of the pool, a bit messy.

 

[Texas Splash]

Not a DE owner, but if the DE is only settling backwards and not blowing forwards to the returns and pool, I would check the easy stuff first:
- Filter air leaks; air getting pulled-into the filter can move water backwards. Check everything you handled last month to include the filter housing O-ring and pressure gauge/air relief on top; listen for any hissing sounds when the system is turned on/off, or perhaps even try some shaving cream in those areas to see if it gets sucked in
- The plunger valve might need a look. It has O-rings as well that may need to be lubricated
- All of the O-rings mentioned should be coated with a silicon-based product (i.e. Magic Lube) designed for pool use.

Let us know if you see any other unusual issues, have more questions, and/or how everything turns out. Others may reply as well, so stay tuned.

 

[acpie360]

Pat, thanks. I think you are right on the air leak because when the pump runs I can see air bubbles in the return. I don't see air bubble if I look down into the strainer lid. Can I assume the leak or leaks will be anywhere after the pump?

 

[mknauss]

Suction side leaks are before the pump. They pull air with the pump on. They also let the system drain back into the pool with the pump off.

 

[Jimrahbe]

ac,

I am not sure what is happening but something is odd...

When you open the pump lid, you let air in the system, which will let the pump basket drain back into the pool through the suction/skimmer line.

It will also let air into the filter, which I would assume would let the filter drain back into the pool through the return lines.

You certainly might have an air leak somewhere, but I can't visualize how that would cause the problem that you are having.

If this were my system, I would breakdown the DE filter, clean and inspect all the grids, inspect and lube the O-Rings and then reassemble everything and see where you are.

Thanks,

Jim R.