Sand filter pressure low

milesvdustin

Well-known member
Jun 7, 2015
134
Marion, IL
Pool Size
27000
Surface
Vinyl
Chlorine
Liquid Chlorine
I got this pool with the house and it has a hayward sand filter. I replaced all the sand and inspected the laterals and everything was in ship shape. 300 pounds of new sand. It seems to work properly and filter fine, but the gauge shows 2 PSI after a backwash. If I add DE i can get the pressure to about 3 or 4, then usually 4 or 5 days after adding DE the pressure creeps up to about 10 then I backwash it and start over. Is that normal for the pressure that low? Pool has 1 skimmer and 3 returns. Should I plug one of the returns? Its in a weird spot below the skimmer and to the right, about 18" lower than the two returns in the corners.
 

milesvdustin

Well-known member
Jun 7, 2015
134
Marion, IL
Pool Size
27000
Surface
Vinyl
Chlorine
Liquid Chlorine
I also feel like when they replaced the pump (who knows when) they should have put a much bigger pump in for this size pool?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
43,998
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Low filter pressure is good. Watch letting the pressure rise so much before cleaning. We recommend a rise of 25% over clean pressure. But your pressures start so low may not be as easy to apply, so go by feel of the water return velocity.

Your pump size is fine. The pumps main function is to distribute chemicals when added and skim the surface. You do not need a high power pump to achieve that.
 

milesvdustin

Well-known member
Jun 7, 2015
134
Marion, IL
Pool Size
27000
Surface
Vinyl
Chlorine
Liquid Chlorine
Sweet, thanks! Ill keep an eye on it and backwash it sooner. I have had it run a few weeks without seeing the pressure go up at all until I add some DE, but my robot and skimmer socks keep the water pretty clean.
 

milesvdustin

Well-known member
Jun 7, 2015
134
Marion, IL
Pool Size
27000
Surface
Vinyl
Chlorine
Liquid Chlorine
Soooo I was adding DE the other day and saw it coming out of my returns just a smidgen. GRRRRR
I backwashed the filter well and noted the pressure as being 1 or nothing, needle barely off the zero post (0-100 gauge)
Pulled the top of the MPV and this is what I found.
20210626_074516_compress99.jpg
Put a new spider gasket in and now my clean filter pressure is 5 psi!
20210626_074525_compress56.jpg
No more DE in the pool!!!!
 

Chad1979

Well-known member
Jul 28, 2019
136
Northwest ohio
Well thats a good find and fix. There are a few folks here whos system psi is only 1 or 2, so dont feel like yours is too low. Now that you have a good gasket and the system is at 5 after a backwash, that is your systems clean filter psi. If your system runs that low psi wise, i would possibly consider getting a pressure gauge with a 30 psi range instead of that 100. It would make it easier for you to check and see when your system starts to get dirty at a glance vs the little movement of a 100 psi gauge. Just a suggestion for the future when this gauge goes bad
 
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