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Thread: Sand Filter high pressure before/after backwash

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    Join Date
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    Sand Filter high pressure before/after backwash

    Hi,

    I have a sand filter and it is running at 19/20 PSI. (The water is green and cloudy.) Even after I backwash for a minute, the pressure doesn't change.

    Do I have a problem with my filter? or is this a normal pressure for a very green cloudy pool?

    Thanks,

    -Matt

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    Texas Splash's Avatar
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    Re: Sand Filter high pressure before/after backwash

    Hi Matt. I suspect your filter is fine. It's your water chemistry that's causing the problem - algae. You need to "SLAM" (link below) your pool. To do so however requires the proper test kit, either a TF-100 or Taylor K-2006C (link below). If you already have one of those you can post a full set of results, but I'm 99% sure that's what you need - a SLAM.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    Re: Sand Filter high pressure before/after backwash

    One minute would never be long enough when I backwash. Do you have a clear sight glass? You should backwash until the glass clears up. Then you should rinse for 30 sec to 1 minute. It stinks to loose all that water but I suspect that your sand is not get clean. There are threads on deep cleaning your sand filter. Mine is in my basement so I haven't done it. Start with running the backwash longer. After that, you can use chemicals per advice given.

    C.N.
    IG vinyl liner 20x40 Pool, Hayward S-240 Sand Filter and Hayward pump in basement
    Indoor Jacuzzi spa 500 gallons, Spa Marvel
    Rochester, NY

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    Re: Sand Filter high pressure before/after backwash

    Hi, Thanks for he responses. The water is now blue in color, but still cloudy. I have been shocking it (3 gallons, around 30,000 gallons of water) every day for five days straight. The pump has been running for weeks. It seems to clear up very slowly. The pressure has only changed by one or two PSI the entire time. I tried to backwash for more then a minute and still the pressure did not change. It is hovering around 20 PSI. The fact that it took so long to clear and the pressure makes me wonder what is going on.

    How do I deal with the cloudy water? I added clarifier hours after the shocking. It has seemed to help. The chlorine is very high.

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    Mr Bruce's Avatar
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    Re: Sand Filter high pressure before/after backwash

    Which test kit did you decide on? Without a proper test kit you're just shooting in the dark. Also, clarifiers may add things to your pool that may make things worse.
    32K gallon Plaster - 1hp Hayward 2 speed Super Pump - Hayward S200 Sand Filter - TF100XL
    Test Kits - Pool Math - Chlorine/CYA/Target/Slam Chart

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    TFP Guide

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    Re: Sand Filter high pressure before/after backwash

    Has this always been the pressure or has it been different in the past. Each pool is different depending on the plumbing so your pressure will unique to your pool. Maybe the normal pressure is 20PSI. Does it ever go up from there? Does the guage go to zero when the pump is off?
    Unknown make 18' above ground (bought used in 1999) Sparco sand filter. Hayward 100,000 BTu heater. 2 speed pump

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    Re: Sand Filter high pressure before/after backwash

    We use the PH/Chlorine/Alkalinity and Stabilizer test strips. Everything has looked high except the stabilizer which has been okay. I have only seen the pressure this year. It does fluctuate one PSI up or down. We used to have a DE filter and that ran around 12 PSI. It does go to zero when off.

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    Re: Sand Filter high pressure before/after backwash

    My pool pump pressure is at 18 psi with a clean filter. I consider mine dirty and backwash at 23-24 psi.
    36' x 18' 20k in ground, Finest Finish grey plaster, Pentair Tagelus 100D sand filter, Hayward Northstar 2hp pump, Jandy LRZ125EN heater, spill over spa, iaqualink controlled automation, Stenner chlorination, natural rock and flagstone coping, 1" glass mosaic waterline tile, SR Smith Vortex slide.

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