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Thread: When to clean my filter if pressure does not rise

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    When to clean my filter if pressure does not rise

    I finished the pool in May 2010. After the plaster dust settled and the water cleared up I cleaned the filter even though the pressure had really never changed. I think it may be due to the size of the filter relative to the size of the pool. It didn't look bad considering how much plaster I sucked up with the vacuum. It's a 450 sq. ft. cartridge filter and the pool is about 15,000 gallons. Since the beginning of last May (almost 11 months now) the pressure has only gone from 15 psi to 17 psi. I've heard the rule of thumb is to clean the filter after it rises 10 psi. At this rate, that will never happen. Is there a time frame that you should clean it out at if the pressure doesnt change?
    15,000 gallon gunite pool, grey plaster with 8' raised spa
    Jandy PlusHP Pump 2 HP Dual Speed
    Sta-Rite 450 Sq. ft. Cartridge Filter
    Cleva-Chlor RP40HD
    Raypak 400k btu heater
    Jandy Aqualink RS-8 One Touch
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    Re: When to clean my filter if pressure does not rise

    A number of people on the forum talk about cleaning their carts once a year, need it or not. Brag, brag...
    --paulr
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    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
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    Mod Squad zea3's Avatar
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    Re: When to clean my filter if pressure does not rise

    Not really. Over sized filters are great for just that reason, long stretches between cleanings. As long as you don't suspect a problem with the pressure gauge you can let it run until you reach that 10 pt rise. If you winterize the pool you would clean the cartridge before storing it for the winter, that would give you an annual cleaning. Enjoy your pool, it sounds great!
    TFP Moderator
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    mas985's Avatar
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    Re: When to clean my filter if pressure does not rise

    I have the same situation and I think is a good thing. Waiting for a pressure rise of 10 PSI is a huge waste of energy. That is an extra 23' of head and will result in a large decrease in flow rate. I wouldn't go past 2 PSI rise but I am very sensitive to head loss.

    Anyway, I will usually clean my filter once or twice a year and rarely see a pressure rise. This year I was lazy so I am waiting until the beginning of warm weather at which point I will clean the filter. I hate cleaning the filter when cold out. So my advice is clean the filter when it is convenient and at least once a year but don't let the PSI rise too much.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: When to clean my filter if pressure does not rise

    If I wanted to soak this monster cartridge in TSP, how would I go about it? It's too big to put in anything. Can I close the valves and soak it in the filter housing? Then drain the housing once it's done soaking?
    15,000 gallon gunite pool, grey plaster with 8' raised spa
    Jandy PlusHP Pump 2 HP Dual Speed
    Sta-Rite 450 Sq. ft. Cartridge Filter
    Cleva-Chlor RP40HD
    Raypak 400k btu heater
    Jandy Aqualink RS-8 One Touch
    Savi Melody 12v LED lights

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    mas985's Avatar
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    Re: When to clean my filter if pressure does not rise

    I use a large plastic garbage can but normally, I don't bother soaking the cartridge unless there is a lot of suntan oil embedded in the media.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: When to clean my filter if pressure does not rise

    Hmmm. There's an idea. So now now only do I have to clean my filter, buy I also need to clean my garbage can. This is going to be an all day project I think. How will I know if there is suntan oil embedded? Can you actually see it?
    15,000 gallon gunite pool, grey plaster with 8' raised spa
    Jandy PlusHP Pump 2 HP Dual Speed
    Sta-Rite 450 Sq. ft. Cartridge Filter
    Cleva-Chlor RP40HD
    Raypak 400k btu heater
    Jandy Aqualink RS-8 One Touch
    Savi Melody 12v LED lights

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    Mod Squad zea3's Avatar
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    Re: When to clean my filter if pressure does not rise

    You might see a scum line around the pool if your household uses a lot of sunscreen. I don't think you would be able to feel it unless it was really bad, and then you would probably had the pressure rise to go with it. I would get a nice big new garbage can and use it only for filter soaking.
    TFP Moderator
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    Re: When to clean my filter if pressure does not rise

    I clean mine every three months. It's no big deal.
    13K Gal., Plaster, SWG, Intellichlor IC 20, Sta-Rite 1 HP Pump, Sta-Rite PLM 300 Filter, Pentair LED, Solar, Screened Enclosure, Great White, TF-100

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    Re: When to clean my filter if pressure does not rise

    Back to the 10 psi rule of thumb, if we could.

    I've been doing some energy calculations for our soon-to-be pool, and I found Jandy and Pentair both suggest cleaning at a 10 psi rise. I put this number into our pump curve, and 10 psi would bring our flow to a halt. I checked a couple other common pump curves and in all cases it would result in a huge reduction of flow. Am I missing something? Or are the filter manufacturers using this number because it makes their product look low maintenance, even though it is not at all practical?
    12,000 gal in-ground, blue granite pebble, Hayward Ecostar pump, 525 sqft cartridge filter, 250 sqft solar panels, TF100 test kit

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    Re: When to clean my filter if pressure does not rise

    Exactly, you are not missing a thing.

    I would never wait 10, 5 nor even a 3 PSI rise. It just doesn't make sense for both energy conservation and keeping the pool clean. Having such a drastic reduction in flow rates would increase turnover time and cause problems in water clarity. However, if I had to clean the filter every week, that would be a different story and I would probably deal with higher PSI rise. As long as you oversize the filter, a 1-2 PSI rise or even less is high enough.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: When to clean my filter if pressure does not rise

    That 1-2 psi instead of 10 psi is also true for sand filters I assume?

    Thanks
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
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    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
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    Re: When to clean my filter if pressure does not rise

    Hijacking just a little......mas985, I have never been fond of the 10psi rise either.....mostly because my normal psi is 9 to begin with.

    Do you think it would make more sense to suggest a percentage rise? So, if your normal psi was 20 and the suggested rule of thumb to backwash was 25%, you would generally be ready to backwash around 25psi. If your normal psi was 10, you would backwash somewhere around 12.5
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: When to clean my filter if pressure does not rise

    Quote Originally Posted by Johnny B
    That 1-2 psi instead of 10 psi is also true for sand filters I assume?

    Thanks
    I usually stick to about 10 psi with my sand filter. It seems that sand filters will actually filter the water better after they are slightly loaded with dirt. With the 2-speed pump, my clean filter pressure is less than .5 psi, and I will backwash when it rises to about 3-4 psi. This usually comes out to be a 8-10 psi rise when in high speed.
    12,800 gallon IG plaster kidney-shaped pool, waterslide, 800 gallon spa.
    1HP 2 speed Sta-Rite pool pump, 1.5 HP Sta-Rite spa jet pump. 2 skimmers, 1 main drain
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    Mod Squad zea3's Avatar
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    Re: When to clean my filter if pressure does not rise

    Being inherently lazy, I only clean my filter when the return flow gets low. That usually coincides with an 8-10 pt rise. When I am a good girl and stay on top of my water chemistry it can take a long time to get to that state.
    TFP Moderator
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    Re: When to clean my filter if pressure does not rise

    I find that I clean mine when it needs it. If I'm going from swamp to clean, like I'm doing now, I'm likely to clean my filter every week or so. My pressure is only up 5psi over where it started but I just know that the filters have to be filthy considering how much cleaner the pool looks than where ti was a week ago. Thus, I clean it todya.

    That said, if the pool stays clear, I'll probably only wash every couple of months as long as the pressure stays low.
    Clearwater, Florida

    12,000 gallon kidney shaped gunite pool
    Pentair Whisperflo 3/4HP Pump
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    mas985's Avatar
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    Re: When to clean my filter if pressure does not rise

    Quote Originally Posted by duraleigh
    Hijacking just a little......mas985, I have never been fond of the 10psi rise either.....mostly because my normal psi is 9 to begin with.

    Do you think it would make more sense to suggest a percentage rise? So, if your normal psi was 20 and the suggested rule of thumb to backwash was 25%, you would generally be ready to backwash around 25psi. If your normal psi was 10, you would backwash somewhere around 12.5
    Yes, I think a precentage rise is a better metric to use although I would probably set the target a bit lower and use 25% as a maximum. If the filter is large enough, even cleaning at 10% shouldn't be a burden. But for people with smallish filters, as pointed out by some, even 25% could be cleaning the filter quite often.

    So my advice to anyone is to clean your filter often enough so as to avoid a substantial PSI rise but not so often that you feel it is a burden.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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