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Thread: Basic question about how a DE filter works etc

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    Basic question about how a DE filter works etc

    I am cleaning my DE filter for the 3nd time since I bought the house last Sept. The pressure was going up slowly until yesterday, when I posted about whether it would harm my filter or pump to have it on at that psi. After I sent the email and kept running it, I continued to check the psi and it went from 18 to about 24 in a couple hours. The pool is pretty dirty after we were on vacation for 3 weeks, definitely I have lost the clarity of the water and it's foggy. I'm working on getting the chemicals sorted as well.

    I must've cleaned the pump basket, filter and sweeper bag about 6 times or more yesterday - thinking it was debris and dirt (I have a ton of dirt on the bottom that may or may not be from the dog swimming) and doghair that might be raising the pressure. It didn't really help.

    Following some instructions I got from simicrintz the last time I cleaned my filter, I backwashed and the water was clear? Is it supposed to be clean when you backwash?

    After the backwash, I popped the top of the filter and took out the panels (can't remember what you guys called them). They came out easily this time (much easier than last time) and I noticed that four or five of them are caked with gunk and the others have nothing on them - including DE. Is the filter supposed to spin in the casing - so in theory all of the panels would get junk on them, right? Anyhow, I popped them out and I'm going to start cleaning them soon but wanted to see if perhaps there is something else I should be checking.

    Finally, is it normal that when I turn off the pump, dirty water from the filter would fill it up a bit?

    Thanks for all your help. Bruce has been great but I thought I'd give him a break from my incessant questioning. I'm getting close to thinking I need to hire someone to help me get this sorted out and I'd really like to work it out on my own.
    Temecula, CA
    16X32 (approx) 20k gal, DE filter, IG, plaster/pebble with diving board & slide
    Whisperflo pump; Pentair SMBW 4000 Series filter... that's all I know! Still learning....

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    JasonLion's Avatar
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    Re: Basic question about how a DE filter works etc

    All of the filter panels, they are called grids, should be coated with DE. Sometimes a little of the DE falls off when you are opening up the filter, but not usually several panels worth.

    When the pool is very dirty it is fairly common for the filter pressure in a DE filter to go up quickly, especially when you have algae. When the water is crystal clear and everything is working well it should go far longer between cleanings.

    Dirty water pushing backwards into the pump usually means there is air trapped in the filter. You want to let any air in the filter out via the air bleed valve on top of the filter. You always need to do that after having had the filter apart. You shouldn't generally need to do that other times, but now and then some air can get into the filter and needs to be released. If there is air getting into the filter constantly, there might be something wrong.

    Did you remember to add 80% of the normal amount of fresh DE after backwashing the filter?
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Basic question about how a DE filter works etc

    JasonLion, thanks for the response. I didn't have the info about adding more DE so the answer would be no. In fairness, the backwashing was in the instructions for cleaning the filter so I was about to replace all the DE so I didn't know that. Thanks for that heads up.

    I'm guessing the algae is starting - it would explain the rise of the pressure and it's obvious from the cloudy water. I better go and get back to work!

    Thanks again
    Temecula, CA
    16X32 (approx) 20k gal, DE filter, IG, plaster/pebble with diving board & slide
    Whisperflo pump; Pentair SMBW 4000 Series filter... that's all I know! Still learning....

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    JasonLion's Avatar
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    Re: Basic question about how a DE filter works etc

    Yes, algae is likely given your description.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Basic question about how a DE filter works etc

    FWIW - here is a thread on DE filters
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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    Re: Basic question about how a DE filter works etc

    Ted, thank you! That helps so much.
    Temecula, CA
    16X32 (approx) 20k gal, DE filter, IG, plaster/pebble with diving board & slide
    Whisperflo pump; Pentair SMBW 4000 Series filter... that's all I know! Still learning....

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    Re: Basic question about how a DE filter works etc

    I received a PM from grrltraveler re. Use and Care for a DE Filter. As it's an offshoot from this thread I'll quote the question and post my response here.

    You sent me the link to this stickie you posted and it was great information, thank you.

    The question I have is about the acid cleaning.... I have rinsed the grids, which are older, and they seem still dirty even though I used my hand to "scrub" off a lot of the grime while I was rinsing. you mentioned them holding the water for more than 30 seconds would be a telltale sign of whether you need to treat them... it does not seem they are holding the water - is there another way to tell?

    I have only had the house/pool since Sept and don't know what they did to the pool - last time the grids were replaced or treated, etc.

    Any help would be greatly appreciated. I did do a full rinse and replace of the DE in the beginning of January and everything seemed to work quite well until the last few weeks when the pressure started increasing, hence the cleaning again.

    Thanks
    Water staying in the grids for ~30 seconds+ after hosing them off is a sure sign that the grid membranes are congested with something and, therefore need the degreasing soak, and possibly the acid soak.

    As they age, have more years of service under their belts, they can become discolored. As long as the PSI hasn't increased over what it was when new and freshly coated, it's only an aesthetic issue (and you can't even see them when the filter is running :P )

    However, something has embedded itself in the fabric and you may want to do the TSP wash and the acid wash to see if that clears them up - if it doesn't you can always bleach them (everyone on this site has a couple gallons of bleach laying around, don't they? ).

    In short, stained grids aren't usually a problem but you can clean them up if you want
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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