DE in sand filter not changing pressure

iammikeb

Gold Supporter
Apr 27, 2020
47
Phoenix, AZ
I followed the guide, but even after two full cups of DE the pressure in my filter did not rise at all. The guide didn’t really indicate whether going beyond two cups was safe or not, so I have not tried any more than the two cups.

Why am I not seeing any change in pressure after adding two full cups of DE to my sand filter?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
30,871
Laughlin, NV
Depends on the filter and how dirty it was when you started. I would leave it for a day or two and see if you have any pressure rise.
 

iammikeb

Gold Supporter
Apr 27, 2020
47
Phoenix, AZ
I’ve tried it twice now, each time after I backwash the filter (which I do on Saturdays). The pressure does not increase even over the span of a few days.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
30,871
Laughlin, NV
You really should wait to backwash until your filter pressure rises by 25% over clean pressure. Not on a schedule. A slightly dirty sand filter filters the water much better.
 
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lorianne621

Member
Mar 6, 2018
23
Climax Springs, MO
We had this problem... among others after purchasing a home with an inground pool. We struggled along while learning all pool basics from TFP but nothing affected the pressure which didn't change much no matter what we did. This year my husband decided to change the pool filter sand. That was indeed our problem. We could not have known what the previous owners had done. They had used construction sand instead of pool sand in the pool filter. We cleaned and reassembled everything. When we opened the pool this year, the pressure was lower than we had ever observed in the past and would change slightly after vacuuming or backwashing the system. Thanks to TFP we now have no issues with pressure. Not sure if this is your issue or not, but if you inherited a system from another person, you might want to investigate further.
 
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Markymarks

Member
Jun 3, 2020
23
SE Michigan
Did you see a white cloud of DE out of a return?

Maybe you can learn from me...I put on a new multi port valve on my filter and his year but since there is no procedure does replacing it I didn’t realize I needed to put a 4’’ section of pvc into the valve so that it would mate to the main pipe in the filter.

Added that PVC and instantly pressure was 1 psi higher than before. Added some DE and pressure up another psi. At same time of having the valve off did a deep clean of the sand and a lot cane out. And been fighting an algae bloom that I’ve been at SLAM chlorine levels. 6 hours after fixing the connection in the filter the pool looks like a completely different pool than this morning.

Remember to lube the gaskets if you do take the valve off.