DE filter keeps rising in pressure


Apr 17, 2021
I cleaned my Hayward DE filter about a month ago as I noticed the pressure was zipping up to about 20 PSI when 10 PSI is normal. By cleaning I mean disassembled and sprayed out with a hose. I then added the right about of DE in the simmer (4lbs) and all was normal for about 2 weeks. Then I noticed again the pressure shooting up again. So Backwashed for about 1 minute and without adding DE just turned it back on. Was fine for about another week then again pressure starting shooting up. That was last night. Backwashed again and pressure back down to 10 PSI. Now this morning less than 12 hours later pressure was all the way up to 30 PSI. A quick backwash and it came back down but its already climbing again.
Why does my pressure keep going up like this?

Thanks for any help.


Gold Supporter
Jun 28, 2017
Fresno, CA
Pool Size
Pressure increases when flow is restricted, we can all agree on this, correct?
Contaminants in your water will plug up a DE filter quickly, especially high levels of microorganisms.
If you are testing your water with a good test kit then post your current numbers as this will provide clues to your problem and solution. A good test kit can also be used to perform an Overnight Chlorine Loss Test which will diagnose if organics in your water are a problem that demands action, like this solution SLAM Process


Gold Supporter
May 28, 2020
North Attleboro, Massachusetts
Pool Size
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
My DE filter behaved exactly this way - clear water the whole time - until I got my own test kit, found this site, and learned how to SLAM. Now I can go half a season or more without the need to backwash.

It's an algae issue whether you choose to believe it or not, even if you can't see it.

If you can't maintain the recommended peroxide level in your pool, that's a big clue.
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Bronze Supporter
Jul 22, 2020
How old are your DE grids?

When we bought our house last year I struggled with the pool for the first few months. The filter pressure kept going up but not quite as quickly as yours. I was only averaging about 10 days between backwashing and replacing the DE. Later in the season I disassembled the filter and cleaned the grinds really well. This had a noticeable improvement however I still wasn't getting the once every 30 days DE replacement I was hoping for.... anyway I bought some new inexpensive grids over the Winter and decided to open the pool with the old grids. When it cam time to swap the grids I took a really good look at the old ones and realized that there was a lot more calcium deposits on them than I realized. Additionally, I never noticed the multiple broken internal fins. I'm guessing under pressure those areas of the grids were collapsing and significantly reducing the filtration area.

The new grids are working great... super pleased. Best $85 I've spent on the pool.

My other theory is that you have some Amish neighbors using the pool when you're asleep....
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Apr 17, 2021
Well I finally fixed this problem. Took a trash can and filled it with water and threw in some automatic dish washer tabs, took out all the grids and rinsed the DE off of them, then let them soak overnight in the trash can. That was a few weeks ago and still have 10 PSI on my gauge so it seems there must have been grease on them. Hope this helps someone


Gold Supporter
Aug 26, 2016
Berks County, PA
I'm thinking that filter cleaner should also remove whatever contaminants are on there. The thinking here on the forum is that it is an algae problem. If such is the case, I suspect nothing will ultimately help other than using chlorine. Not sure if you are chlorine or baqua? I'm up to 16 today after a starting pressure of a bit under 14 - not worried about fluctuations but when it starts to creep up to 17-18 within a few days to a week, I know I'm in for a short cycle. It's not so much that I mind the work, but two things really bother me. One is the constant worry about the pressure going up and the other is the large accumulation of spent DE that winds up seeping down in the lawn and eventually creating sort of mini pitcher's mounds. The other week I dug alot of it out and carted it over to woods next to us, but hate to do that as well since the stuff is a possible hazard. I really need to take care of these issues once and for all. If chlorine is the way, then that's what I'll need to do.
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