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Thread: Sand filter pressure reading 0

  1. #1
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    Sand filter pressure reading 0

    I loaded my sand filter (triton tr100, 450 lbs sand) for the first time last night, rinsed to waste and started filtering. The flow is good at high and low speed. I am concerned because the pressure gauge continues to read 0 even after 12 hours of operation ...



    There must be some pressure because water shoots out of the bleeder valve about 4 feet when it's opened. Why is it reading 0 ? IMO this is not a good place for a pressure gauge. I can make the gauge move by partially closing the gate after the filter.

    There is a fitting for a gauge on the back of the valve ...



    Should I try another gauge here ? Seems like a better place.

    Thanks for the forum and help.
    20x40 IG Vinyl
    33k Gallons
    Triton TR-100 Sand Filter
    Pentair WFDS-6

  2. #2
    Administrator JasonLion's Avatar
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    Filter gauges tend to break fairly frequently. Fortunately they are not very expensive to replace. I would try putting in a new one and see if that solves the problem.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    TFP Admin. Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  3. #3
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    Hey, Brian,

    I've got the same multi-port valve and a TR-140 filter.....my guage is in the same place and I've replaced the guage once in 4 years....expect to do so again sooner or later. I'll bet a new guage will solve your problem.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
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  4. #4
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    Thanks for the quick replies. I went to Leslie's for the first time at lunch and got another gauge. I think it was the cheapest thing in the store. ($7) I also got some skimmer socks, ($9). The only hard sell he tried was somthing about the $40 phosphate removers I needed since my water came from a truck. He was friendly and answered lots of questions. But, it was kinda hard to watch the poor guy in front of me spend $513 opening his pool.

    I'll post again after I install the gauge.

    Thanks again.
    20x40 IG Vinyl
    33k Gallons
    Triton TR-100 Sand Filter
    Pentair WFDS-6

  5. #5
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    When I got home last night I shut the pump down and replaced the gauge. Turned the pump back on, new gauge also reads 0. Somewhat discouraged, I went ahead and hooked up the vacuum (first time) and did a 'blind' cleaning in the deep end (can't see the bottom yet), then cleaned up the break and shallow end fairly well. The vacuum seemed to work ok. When I finished I checked the pressure, reading 5 lbs, things were looking up. I shut the pump down again to remove the vacuum plate. When I turned it back on, pressure read 0 again. Still on 0 this morning. I resisted the temptation to dump a bucket of dirt into the filter until I had a chance to post today.

    I should probably ask some questions, like -
    - What causes pressure to build in a sand filter ?
    - I installed 2" plumbing for everything except what I got from the pool company, specifically the skimmer and return fittings, they are 1.5". Could this be causing a problem ?
    - What tests can I do to find the problem ? I really don't want to empty that sand if I don't have to.

    Pics of my setup. You can see the 1.5" to 2" conversion in the skimmer pic :




    Thanks for the help.
    20x40 IG Vinyl
    33k Gallons
    Triton TR-100 Sand Filter
    Pentair WFDS-6

  6. #6
    Mod Squad JohnT's Avatar
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    You would have pressure even if you didn't have a filter, due to plumbing resistance. I'd loosen the gauge while the pump is running and see if water or air comes out.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

  7. #7
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    Thanks for the quick reply. Yes, I did that last night, water came out. Got kinda wet and looked silly trying to get it back in without shutting the pump down.
    20x40 IG Vinyl
    33k Gallons
    Triton TR-100 Sand Filter
    Pentair WFDS-6

  8. #8
    Administrator JasonLion's Avatar
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    After a broken gauge the next most likely issue would be a suction side blockage, but that would restrict flow and cause the vacuum not to work, so that seems unlikely. It is possible to get blockage in the pipe leading to the gauge (inside the filter) but then it would never have gone to 5 psi.

    The vacuum restricts the flow on the suction side, which normally causes the pressure at the filter to go down. I am mystified.

    What size pump do you have and if two speed or multi-speed, what speed do you run it on?
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    TFP Admin. Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  9. #9
    Mod Squad JohnT's Avatar
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    Quote Originally Posted by brianspool
    Thanks for the quick reply. Yes, I did that last night, water came out. Got kinda wet and looked silly trying to get it back in without shutting the pump down.
    If water comes out, you have pressure. Two bad gauges??????
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

  10. #10
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    Hi Jason, thanks for the reply. The pump is a Whisperflo 1.5hp 2-speed (wfeds-6). I had it on low last night when I was working with it. I tried the vacuum with the pump on high but it seemed like it was sucking more air that way. I am also confused. I am going to call the plumber (in-law) back and see if he has any ideas.

    John, I was waiting for photobucket when you posted. I'm thinking like you, maybe gauges or maybe the opening in that plastic 'dome' where the gauge screws in isn't big enough ? (it looked like about a 1/4" opening). Maybe the plumber has an accurate gauge he can hook up.

    Thanks for the help.
    20x40 IG Vinyl
    33k Gallons
    Triton TR-100 Sand Filter
    Pentair WFDS-6

  11. #11
    Administrator JasonLion's Avatar
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    The pressure can be quite low when the pump is on low speed. Some pressure meters stay at zero when the pressure is only a couple of pounds. Other than that nothing occurs to me.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    TFP Admin. Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  12. #12
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    I tried the vacuum with the pump on high but it seemed like it was sucking more air that way.
    No air whatasoever should be entering the system. Are you saying you have air bubbles in the pump basket when the pump is running?
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
    TFTestkits owner
    TFTestkits , PoolMath , Pool School

  13. #13
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    Hi Dave. No, I don't think so. There is usually a 'pocket' of air in the dome on the pump when I first start it, but after it runs a while it's gone. I was fumbling around trying to get the hang of the vacuum hose and low speed gave me more room for error. I lost prime a couple of times on high speed. I finally got the water hose out and filled up the vacuum hose. Once the memory comes out of the hose it will be easier. I just left it in the pool stretched out.
    I talked to the plumber this morning, he seems to think like us that either the gauges or the gauge mount may be the problem. He is coming by tonight to check it out.
    Thanks for the help.
    20x40 IG Vinyl
    33k Gallons
    Triton TR-100 Sand Filter
    Pentair WFDS-6

  14. #14
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    I gotcha'! As long as you are moving a good volume of water, there is pressure in the system (because of the resistance to the movement) and there is no harm done if the guage is showing zero.

    So, if you simply put your hand over a return and can feel a really good voume of water coming out, you're good to go. Two bad guages is amazingly coincidental, however.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
    TFTestkits owner
    TFTestkits , PoolMath , Pool School

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