Quick Jump in Filter Pressure After Cleaning - should I be concerned?

[Mark-in-NC]

Yesterday I disassembled my Jandy DEV60 pool filter and thoroughly cleaned everything before reassembling. The velocity of water coming out of my pool outlets had seemed pretty sluggish, so I suspected that the filter was clogged. When I opened it up, my suspicions were validated, as it was filthy and clogged with what looked like 50 lbs of DE (see attached photos). BTW, I thoroughly backwashed prior to opening up the filter for cleaning.

After reassembly and the addition of new DE, the velocity at the outlets was greatly improved, and the filter pressure gauge read about 22 psi (before cleaning it was 31 psi). This morning before leaving for the office I took a quick look at the filter pressure and it was reading about 27/28 psi. So in about 12 hours the pressure jumped from 22 to 27/28 psi.

Should I be concerned about this relatively rapid increase in pressure? I have seen here on TFP that backwashing is recommended when the pressure increases by 20-25% of the clean pressure. Should I backwash and add new DE?

My wishful thinking is that it took some time for the filter to run and thoroughly set the DE before the "real" clean pressure registered on the filter pressure gauge. However, I guess it's also possible that prior to cleaning the filter was very inefficient, and after cleaning it picked up a lot of dirt from my dirtier-than-normal pool. Prior to cleaning the pool was crystal clear during the day, but at night I could see some particulate in the pool lights.

Thoughts? Thanks in advance.

 

[ajw22]

What test kit do you use?

Can your pool pass a Overnight Chlorine Loss Test?

 

[Jimrahbe]

Mark,

Pressure quickly going up after the filter is cleaned, is almost always due to an algae bloom, even if you can't see it yet.

You need to do an Overnight Chlorine Loss Test (OCLT)..

Overnight Chlorine Loss Test

Thanks,

Jim R.

 

[Mark-in-NC]

I use a Taylor K2006C-SALT for all testing. I can perform the OCLT test tonight. If I lose more than 1 PPM of FC I will start the SLAM process.

Anything else I should be aware of?

 

[Mark-in-NC]

"Pressure quickly going up after the filter is cleaned, is almost always due to an algae bloom, even if you can't see it yet."

I forgot to ask: Is the algae bloom related to the filter cleaning? Does the cleaning process set loose some algae into the water?
Just curious. Thanks

 

[ajw22]

"Pressure quickly going up after the filter is cleaned, is almost always due to an algae bloom, even if you can't see it yet."

I forgot to ask: Is the algae bloom related to the filter cleaning? Does the cleaning process set loose some algae into the water?
Just curious. Thanks

No & No.

 

[Mark-in-NC]

The warnings of an algae bloom had me very concerned, so I ran home at lunch to check my pool. The filter pressure gauge was back to 22 psi (pic).

I also ran a few tests:
FC: 10.5
CC: 0
PH: 7.6
CYA: 80

I am fairly confident that I'm not having an algae bloom, but I'm going to do the OCLT just to be sure. My FC has started to run a little high because I had been bumping up my SWG % to maintain FC. Once the flow was increased back to a normal level after cleaning my filter, my FC started rising, so I dialed the % back.

What would have caused the high pressure reading this morning (27/28 psi)? I will continue to monitor closely, but I'm hoping it's just an anomaly.

 

[Jimrahbe]

Mark,

You may not have algae, but the first thing you need to do is make sure by doing the OCLT.

Basically your filter is filtering out 'something'.. That is why the filter pressure goes up.. The dirtier the filter, the harder it is to push water through the filter, the higher the filter pressure will be..

If not algae, what can it be?? Has to be something in the water that the filter can capture.. Dirt, sand, cement, or???

I assume you just hosed off your DE grids, and that you did not soak them in anything.. Is that correct?

Keep in mind that filter pressure is not how well your pump is doing, but how poorly your filter is doing.. Lower PSI is almost always better.

Thanks,

Jim R.

 

[SecoSteve]

I have the same filter and that starting psi seems high. I know all pools are different, but my clean psi is around
10-12psi. How much DE did you add, and how did you add it? Did you bleed out any air at the top of the pressure gauge?

 

[Mark-in-NC]

Jim,

I am definitely going to do the OCLT and then I'll post the results.

And you're correct; I only hosed off the DE grids. This was my first attempt at cleaning a DE filter, so I only planned on hosing them off, but I did a very thorough job.

Do you recommend soaking them in muriatic acid, or something else? What do you use to soak them? A big plastic tub or storage container?

I did see a youtube video that suggested maintaining 2 sets of grids so that you can quickly change out one set of grids after the filter cleaning, then cleaning the second set so that they're ready for the next filter cleaning. What do DE grids typically run? Might be a little expensive...

 

[ajw22]

You had low FC for your CYA 2 months ago which is when algae could have taken hold in your water.

 

[ajw22]

Jim,

I am definitely going to do the OCLT and then I'll post the results.

And you're correct; I only hosed off the DE grids. This was my first attempt at cleaning a DE filter, so I only planned on hosing them off, but I did a very thorough job.

Do you recommend soaking them in muriatic acid, or something else? What do you use to soak them? A big plastic tub or storage container?

I did see a youtube video that suggested maintaining 2 sets of grids so that you can quickly change out one set of grids after the filter cleaning, then cleaning the second set so that they're ready for the next filter cleaning. What do DE grids typically run? Might be a little expensive...

DE Filter Use and Care - Further Reading

www.troublefreepool.com

 

[Mark-in-NC]

I have the same filter and that starting psi seems high. I know all pools are different, but my clean psi is around
10-12psi. How much DE did you add, and how did you add it? Did you bleed out any air at the top of the pressure gauge?

Best I can recall, my filter pressure has always been in the 20-30 psi range. The pool was built in 2022, and first opened at the end of the summer in '22. For the first 6 months or so the pool builder provided some service, but they never mentioned that the filter pressure seemed high.

I added 10 coffee cans of DE. The manual says 12 cans, but TFP recommends 80-90% of the mfg recommendation.

I first mixed the DE in a large bucket with pool water into a slurry and then slowly poured it into one of my strainers.

Yes, I bled out the air in the pressure gauge.

 

[Mark-in-NC]

Youhad low FC for your CYA 2 months ago which is when algae could have taken hold in your water.

View attachment 602234

Yeah, that was before I started following the TFP chart. Prior to that I was just going by Jandy's recommendation in the SWG manual:

"Free Chlorine 1.0 - 3.0 PPM. Continuous exposure to levels above 3.0 PPM may cause corrosion of pool metals."

Since then I have tried to stick very closely to TFP guidelines.

 

[Mark-in-NC]

PROBLEM SOLVED! My pool has a floor cleaning system, and when the floor system is running it looks like there is enough back pressure to increase the pressure inside the filter.

My floor system is scheduled to run from 7:30 to 10 every morning. When I checked the filter pressure yesterday before going to work it was 29 psi (it was 21 the night before after cleaning). When I came home at lunch yesterday it was 21 psi. I was going to run the OCLT last night, but I held off for a day because I wanted to decrease the PH a little before testing (I added some muriatic acid yesterday). This morning before leaving for work I checked the pressure again and it was back up to 29. When I went home today at lunch it was back down to 21. I became suspicious because the pressure changes were so uniform. I tested the different filter modes on my system and, sure enough the pressure jumps up to 29 psi only in floor mode. I didn't notice it until after cleaning the filter because prior to the cleaning the ambient pressure in the filter was 30/31 and didn't affect the filter pressure.

I don't know why I didn't suspect this in the first place. In my defense I just took a quick glance before work, so I wasn't in analysis mode. Regardless, I'm thinking of changing my name to Heimer Moore Hahn.

Follow up question: Should my floor system be causing the filter pressure to jump up?

 

[ajw22]

Put that you have an IFCS in your signature. That is important to know in discussing future problems.

Your filter pressure will change as your IFCS valve cycles.

Show us pics of your plumbing.

@proavia can help.