DE Filter Clean...Now High PSI...


Oct 14, 2013
So I get a notice a week or so ago from my pool service company that my filter was due for a cleaning. I have a Pentair FNS DE filter. Being somewhat of a DIY'er, I decide I am going to perform this with the help of YouTube. I break open the filter, remove all the grids clean and inspect them (no tears), and then put the filter back together. When I fire the filter up, the PSI immediately shoots up to 35 PSI, and this is before I put the DE powder in. I know something is wrong, but I add the DE powder anyway, and the pool immediately clouds up. I then perform a backwash but this does not fix the high PSI problem. Also, when I turn on my Polaris booster pump, it makes a weird noise and the Polaris does not move. I have a caretaker in floor system and I am not sure that is operating correctly either. Before the attempted filter cleaning, everything was running fine with the PSI at 10 to 15.

Anyone have any idea of what the issue may be? I am pretty confident that I got the filter grids reassembled correctly. In my research, I came across the possible issue of an air leak, so I got some incense and put it all around the pump parts and didn't notice any of the smoke being sucked in. The pool company is scheduled to come tomorrow (they come once every two weeks), but I'd like to not get raped again on a filter clean, etc since I just did that (they got me pretty good on a light repair recently).

I am including pictures of my pump system. I'm really not sure how the levers are supposed to be turned. When I turn the one that I circled in blue, the Polaris fires up bit the Caretaker system appears to be dead. Any help would be appreciated.

2020-09-07 12.07.12.jpgIMG_20200907_120721.jpg2020-09-07 12.07.33.jpgIMG_20200907_120906.jpg
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Gold Supporter
May 20, 2020
Katy TX
Did you bleed air from your filter? if you twist the black ring below your pressure gauge, it will move about 45 degrees and bleed air until water shoots out. Then turn it back closed - all the way to seal it.
With regard to the picture with the 2 way valve circled. The part pointing left that has the word OFF on it indicates that no flow is going to your booster pump and 100% flow is going the opposite direction (the way the handle is pointing). You may want to turn it 90degrees so you have 50% to each return.
Likewise, on the valve you show listed as MAIN Drain, that is at 50% suction from the drain as handle is across the valve. If you point it down or up the valve will be either 100% open or 100% closed for the main drain. Your other suction lines do not seem to show a valve on them individually.
On the valve shown without a handle - it control suctions - from either the right side (I assume a skimmer) and the main drain and from the left side (unknown - do you have a spa?)
Please provide some more details and we can possible help out. Need to know if you have a spa, how many return jets in the pool, confirm only 1 main drain (or if you have a spa - does it have a main drain).
Your return to the pool - it shows splitting into 2 pipes based on what I can see in the picture. Do you have a water feature?
Also - your picture does not show where the return from the booster pump is going - that is the flexible pipe exiting out of the top of the booster pump.
That is all I can see from the pictures shown.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

The Main Drain in your pics above is set to 100% open..

It appears to me that your pool does not have normal returns back to the pool and that all the water must pass through your in floor cleaning system (IFCS)

Your problem is not an air leak, but something is blocking the water returning to the pool.. This means the filter or your IFCS..

Assuming that you did the filter correctly, it points to something in the IFCS.. If this were my pool, I would removed union going the IFCS and fire it up for a few seconds and see what the pressure was. This should tell you if the problem is in the IFCS or the filter...

That said, make sure the pressure gauge is good.. It needs to fall back to zero when the pump is off.


Jim R.


In The Industry
Jan 9, 2020
Check the screen on the caretaker valve, it is on top of the valve, loosen the two unions and remove the 90' pipe assembly on caretaker valve, the screen sits on top, make sure the screen goes back in with the screen up like a mountain, not down like a bowl.

The way the jandy valve is set in the pic, shows all flow back to caretaker, if the screen is clogged that will explain high filter psi.

A lot of people don't even know there's a screen there...
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Oct 14, 2013
Appreciate the tips everyone. The pool guy should be coming sometime this afternoon, so we'll see if he figures it out without bending me I had forgotten all about the Caretaker valve screen. I did the re-build on that caretaker a couple of years ago and should have known to check that. If it's not resolved when I get home today, I'll take a look at that.