Been dealing with this for over a year. Any thoughts?

rgnbull1227

Well-known member
Jun 3, 2013
72
Pool Specs. 48,000 gallon free form pool. Saltwater, Pentair SVRS Variable Speed Pump, DE Filter, Heat Pump. 2 Main Drains. 2 Skimmers, 12 Return Eyes. ( 1 valve controls 2 Jets, 1 Valve controls 3, 1 valve controls 6(sundeck) and 1 Valve controls Waterfall.
Pool is crystal clear. Just opened and have been dealing with this problem since last season. So, I open the pool this weekend, make all connections. startup, all working great, add the DE (10 Coffee Cans). Running at 2500 RPM, Pressure is 20PSI. Add 600lbs of Salt and let run. About 3 hours after starting. I notice the return jets flow diminishing, pressure on Filter same. ran 24 hrs. Next morning, not even a hint of surface motion from jets, still running 2500RPMS and pressure 21lbs. Quick backwash, rinse and restart (did not add anymore DE) and restart. 2500 TONS of surface flow from jets, pressure 20PSI all good. 2 hours later, surface motion slowing down again, 4 hrs no surface motion. Pressure 20PSI and still 2500 rpms. If I do a quick backwash, after restarting the flowis as should and then slowly drops but the PSI on Tank stays constant. Any ideas as its not turning the water over enough unless I backwash. Mind you, haven not added more DE since initial recharge to see if its was actually the filter clogging.
Frustrated and thanks in advance for any insight.
 

Jimrahbe

Mod Squad
TFP Expert
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Jul 7, 2014
21,861
Bedford, TX
rgn,

I can understand your frustration, because what you say is happening does not make much sense. :(

Your symptom of course is that the filter is getting clogged with algae, but since your pool is clear and the filter pressure never goes up, that is a puzzle..

I suppose you could have a bad gage, but then without DE in the system I would not think the filter would clog very quickly...

If me, I'd try running it on recirculate and see if the problem still happens, if so it would eliminate the filter.

Let's see what some of our experts think...

Thanks,

Jim R.
 

rgnbull1227

Well-known member
Jun 3, 2013
72
Being that its a variable speed pump when I crank up the speed or when priming the pressure gauge goes to 30PSI. Then as the pump drops RPMS down to desired RPM, the pressure drops in tandem so I do not think its the pressure gauge.
Thanks for the input and yes, this is frustrating! :)
 

JohnT

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Mod Squad
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Apr 4, 2007
9,959
SW Indiana
Pool Size
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Have you backwashed without adding DE? This can cause the grids to get clogged on a DE filter and will require disassembly for a more thorough cleaning. A thorough cleaning may have been what you needed to start with if you hadn't done so already.
 

rgnbull1227

Well-known member
Jun 3, 2013
72
Opened pool Sunday. Took grids out and did a very thorough cleaning. Then added 10 coffee cans on startup. By the eve, the flow dropped. After reading Jimrahbe post, I went ut to try the pool in Recirc to see if the pressure changed. Sure enough I went out and after only 1 hr after Backwash, the return flow was very low. Shut pump off, put on recirc and tons of return line pressure flow. Wonder if I am getting a suction side air leak and causing Backpressure.

- - - Updated - - -

1 additional note. The Pump Basket shows no air or bubbles. So I assume either very tiny bubbles or an airleak after the strainer basket but before the filter.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
39,723
Laughlin, NV
Pool Size
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Chlorine
Salt Water Generator
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If the problem went away on recirculate then the problem is with the filter. You do not provide any specs in your signature (which I would suggest you complete if possible - really helps) to help out those with more knowledge on that type of filter.

Take care.

- - - Updated - - -

If the problem went away on recirculate then the problem is with the filter. You do not provide any specs in your signature (which I would suggest you complete if possible - really helps) to help out those with more knowledge on that type of filter.

Take care.

Pool School - Read This BEFORE You Post
 

mknauss

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May 3, 2014
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Laughlin, NV
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Pulled up the manual for that filter -- I think you said you ran it without DE? See below from the manual ==

Never operate filter in excess of three (3) minutes without use of diatomaceous earth. Diatomaceous earth is the substance
that filters the water, the filter cloth merely supports the diatomaceous earth. Operating without diatomaceous earth will
damage filter elements and shorten filtering cycles.
 

xyz

Gold Supporter
Sep 8, 2016
641
Escondido/CA
The good news is you have isolated the problem to the filter.

I assume all last year you would get "tons of flow" at 2500?
 

rgnbull1227

Well-known member
Jun 3, 2013
72
No last year, same thing happened. Drove me nuts.
Mknauss-I charged the filter with DE on Sunday, did a quick 15 sec backwash and did not recharge the filter. There is still DE in the filter just not the fill 12 cans required.
 

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rgnbull1227

Well-known member
Jun 3, 2013
72
Something I just noticed. I pulled the Pump basket to empty and I notice what looks like a piece of the o-ring from the diffuser protruding into the basket area. Would this allow Air into the system if this O-Ring is broken or deformed?
 

xyz

Gold Supporter
Sep 8, 2016
641
Escondido/CA
OK, so I assume at some point in the past you got consistent high flow rate.

You get good flow rate when initially charged with DE, so it is very likely the filter elements. You can verify this by running the filter without them; but I'd focus on the elements, this verification is very likely unnecessary.

So maybe time for a good deep cleaning of the elements. So, get that baby clean. Deep cleaning includes soaking in a degreasing solution [suggestion is TSP and dishwasher detergent]. Get em good and clean.

Also, if you have backwashed and recharged multiple times, you may be over charged the filter. When you backwash, you don't necessarily lose all the DE.

So get the elements good and clean, and then immediately add DE. From the DE cleaning post in pool school:

[h=2]Re: Use and care for DE filters[/h]
After 10 yrs dealing with my 30 yrs old Purex DE I finally found a way to deal with the problem i've had, clogging too soon. When mixing DE with water, add as much water as possible and pour as slowly to the skimmer as possible. While pouring, I even use garden hose to add water to the bucket. I think this makes all the DE to coat the grids gradualy and more evenly , not staying at the bottom of the filter. Filtering will be more efficient and backwashing is much faster. The lighter the mixed (more water) and slower the pouring the better the result . The other thing is to use less DE than what recommended. I used 6-8 cups instead of 10 and my water is still clear and the pressure has been stable for a long time (I also use skimmer bag). After a backwash, I never refill the whole amount again, probably 2 cups less. I figure there is no way a backwash will get rid of all the DE.

But I can't find replacement part for the valve so I have to get a new filter. I decided to go with cartridge to deal less with internal parts. When it comes to pool, to me, the less parts and electronics is better. We only swim 2 months out of the year and down time during that period is not good.


The DE cleaning tutorial:
Use and care for DE filters






- - - Updated - - -

Interesting. Is the pump losing prime?

If not, probably not the problem.
 

mknauss

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May 3, 2014
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Laughlin, NV
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Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
The diffuser seal could be it -- I just copied this from Inyo Pools website ---

Diffuser Gasket

Symptoms

Losing prime
Low water pressure

This important but sometimes forgotten part, the diffuser and its gasket enhance the pulling power of the motor and impeller, enabling the pump to prime itself. Located at the tip of the diffuser, the gasket seals the diffuser/impeller assembly to the front part of the housing. The funnel-like diffuser is then able to focus the impeller’s pulling energy, increasing its strength. This aids in priming and maintaining water pressure.

Oh - and thank you for the signature data! That is great --- lead me to the above info.
 

rgnbull1227

Well-known member
Jun 3, 2013
72
XYZ. As stated above, the filter was cleaned thoroughly on Sunday. No media whatsoever. No oils possibly. But again my issues are a few hours after a quick backwash. Now that the pool is in recirc, no pressure issues. As for the O-Ring, I have no issue with losing prime etc. What I am thinking the issue could be with the o-ring is allowing air to get into the filter and causing backpressure reducing return flow. I am going to pull out the Filter Grids and see if its the grids or a backpressure issue.
 

duraleigh

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Apr 1, 2007
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Well, you might be complicating things. You could have a chemistry issue and not a filter issue.

So, if filter and pump act normally at startup and then flow stops (but pump is providing the same "push"), what is causing that flow stoppage? Doesn't it have to be the filter clogging up?

That is further confirmed by the backwash which unclogs the filter and then the cycle starts all over.

What is clogging your filter? Algae. You likely can't see it cause it's in it's early stages but I think your pool is about to turn green.

The one thing that doesn't fit is the pressure not going up. A faulty gauge is my best guess.

Can you post a full set of test results and tell us how you have been managing and testing the pool water chemistry?
 

rgnbull1227

Well-known member
Jun 3, 2013
72
Opened the filter. I see the breather looks blocked. Maybe thats causing backpressure? Looking at the grids does this look clogged? I did not backwash before opening filter.
 

SoCalGuy

Well-known member
Nov 16, 2015
171
San Diego
Yep, clean the breather. That looks like a pretty healthy coating of DE. We have the same FNS filter. Ours does a good job of filtering with quite a bit less DE than you have on there. What size coffee can are you using to measure?
 

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