Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 11 of 11

Thread: sand filter questions

  1. Back To Top    #1

    Join Date
    Mar 2009
    Location
    Charlotte, NC
    Posts
    489

    sand filter questions

    I am new to sand filter use, (had a DE filter before )
    I have question re sand filters
    With fresh new sand, the psi was 14, so that is my normal starting pressure. It is 14 if only the drain only is open. If skimmer only or both skimmer & drain are open (the usual scenario) the psi is 18. Both starting points are ok with respect to when I need to backwash? I can just go 10psi or so beyond either # depending on what is open .

    Wash glass or whatever the term is, the glass like bubble that you look at to see when the water clears. It unscrews, for cleaning? Can leak/sputter water just a tad (doesn’t bother me), any worries. You guys ignore it & look at the water exiting to waste to see when the water is clear? When the water starts out clear but the psi indicates backwashing (so there is no “water to observe go from dirty to clear) you go by how many seconds in my case? (hate to waste the water). I just keep testing/reducing backwashing time to see how quickly I can get to the start 14 psi, right? To date, with heavy opening debris, it takes maybe 20-30 seconds. The manual says backwash 3-5 minutes!? I'll be adding an inch of water ( I Exaggerate).

    At this startup, 2 or 3 times when the psi was up & indicated for backwashing, the pump basket had maybe ¼ the water it should!. Can’t be good on the motor, or is it ok. I don’t recall way less water in the pump basket with my old DE filter when the pressure rose.
    You guys like to Rinse 5-10 seconds after each backwash, right?

    No need to use the air relief valve? You never do when it starts from a timer? Or you use the air relief valve only when it starts out dry (no water, & water is added for the 1st time at the 1st startup of the season or with new sand)? Or you use the air relief valve only when the pump basket comes off for cleaning resulting in some air getting in the lines?

    Best to try to always move the MPV in the same direction?

    When is the "Closed " position on the MPV used ( I realize no flow & never w pump running)
    Any other trips welcomed too.
    Thanks
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

  2. Back To Top    #2
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    Location
    SouthWest Alabama
    Posts
    21,776

    Re: sand filter questions

    Yeah 10 psi above normal, so if it's normally 14 with the main drain open then it's 10 above that.

    The clear bubble is also a vacuum relief valve on mine and once in a while it'll drip/sputter a little water.
    Because mine is plumbed into a drain I use the bubble to tell when the backflush is clear. It always starts out clear but soon clouds up as it starts flushing dirt from the sand.
    I rinse until the water in the bubble is clear.

    Actually when the pressure on the filter goes up the pump should be moving less water and therefore have less suction pressure so the basket should remain full.

    I've only used the air relief valve a few times, like when I knew I had introduced air in the pump/filter. Even then it'll purge it out after running a few minutes.

    Can't comment on the last two.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  3. Back To Top    #3

    Join Date
    Dec 2009
    Location
    Central Massachusetts
    Posts
    2,677

    Re: sand filter questions

    Quote Originally Posted by Johnny B

    Best to try to always move the MPV in the same direction?
    I dunno, maybe an old wives tale. I generally turn mine in the same direction. It goes both ways, but I'm in the habit of going clockwise with mine.

    Quote Originally Posted by Johnny B
    When is the "Closed " position on the MPV used ( I realize no flow & never w pump running)

    Put it to close when you close down and winterize for the season.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

  4. Back To Top    #4
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,887

    Re: sand filter questions

    Closed is normally used when your equipment is below the level of the pool water. In that situation you turn the valve to closed when you are opening the pump strainer basket so the entire pool doesn't try to drain out through the strainer basket. This isn't important if your equipment is above the level of the pool water.

    For winterizing there is often a winterize position on the valve.
    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

  5. Back To Top    #5
    New2Me's Avatar
    Join Date
    Jun 2008
    Location
    SW Indiana
    Posts
    322

    Re: sand filter questions

    I used the "closed" position every time I open the system. I turn off the pump, closed the inlet suction valve and turn the MPV to "closed." Now you can open the pump, empty/clean the strainer basket, or check/clean the ECG cell and not have the filter siphon itself empty. Close everything back up and open the valves right before you turn the pump on, and the prime time is almost zero, because the piping is all still full. If it won't stay full, time to start the leak hunt!
    22 x 40 IG vinyl lined, 23,570 gal.
    1 hp. Pac-Fab Challenger pump 300# sand filter
    Intex 8110 SWG, Hayward CL220 offline feeder
    Hayward 250K Btu gas heater
    Aquabots

  6. Back To Top    #6

    Join Date
    Mar 2009
    Location
    Charlotte, NC
    Posts
    489

    Re: sand filter questions

    Quote Originally Posted by Bama Rambler
    Actually when the pressure on the filter goes up the pump should be moving less water and therefore have less suction pressure so the basket should remain full.
    Just so I'm clear, ...so the basket "wouldn't" remain full?
    I never noticed this on my old DE filter. I just assumed that if that basket wasn't full that it was harmful/stressing the motor. I guess so long as there is SOME water flow the motor is ok?
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

  7. Back To Top    #7
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,887

    Re: sand filter questions

    Normally, the pump basket should be full of water, or have one small bubble. Usually, if there is a lot of air in the pump basket, you have a problem. However, now and then there can be a significant amount of air in the basket even when everything is fine (but that is kind of unusual).
    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

  8. Back To Top    #8

    Join Date
    Mar 2009
    Location
    Charlotte, NC
    Posts
    489

    Re: sand filter questions

    Quote Originally Posted by JasonLion
    Normally, the pump basket should be full of water, or have one small bubble. Usually, if there is a lot of air in the pump basket, you have a problem. However, now and then there can be a significant amount of air in the basket even when everything is fine (but that is kind of unusual).
    The air is only when it is time to backwash, & not 1 or 2 psi earlier. What is your diagnosis? FWIW, the water level can get 1/2-inch too low at times


    Backwashing questions:
    1- if you backwash & upon resuming filtering, the pressure returns to the hopeful expected starting psi, you have backwash successfully or not necessarily? Reason I ask, I can’t really see “dirty water going to clear” either in the bubble or out the pipe, it all looks clear to me from the go. I have been backwashing about 12-15 seconds & each time, the pressure lowers to the ideal start pressure. The manual said Bwash 3-5 min. What do you guys find (so many variables for sure)

    2- Simply turning the pump Off ( no backwash or anything, just Off), doesn’t affect the pressure the next time it starts up, does it? Suppose your range is 10-20 psi, you turn the pump off at 15 psi (so not time for the 20 psi backwash) for a few hours; at the re-start, the pressure should be 15psi, or it doesn’t necessarily work that way?

    Thanks
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

  9. Back To Top    #9
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,887

    Re: sand filter questions

    You need to backwash much longer. When you first start backwashing you will get clear water. It can take 10 to 30 seconds for the water to turn dirty, once it does it can stay dirty for a while.
    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

  10. Back To Top    #10

    Join Date
    Mar 2009
    Location
    Charlotte, NC
    Posts
    489

    Re: sand filter questions

    Thanks Jason, a big help as always.
    So I backwashed for 30 seconds (night, can't determine clarity) & I didn't have to Bwash again for 3 days. Today I backwashed for 1 minute so I'll be seeing how that does, entire time looked clear to me. Further comments always appreciated.

    I am going to edit my posts a different thread based on what I'm learning on this thread.
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

  11. Back To Top    #11
    Molson's Avatar
    Join Date
    Apr 2008
    Location
    Midland, Ontario
    Posts
    479

    Re: sand filter questions

    For what its worth, I opened to a really dirty pool this year, been vacuuming every other day since the initial clean up, I've only had to backwash three times. Once the pool is clean, I only back wash when required, sometimes it can go two months, or longer if the water and floor stays clean.
    40 x 16 IG Vinyl. Goldline SWG
    160 Sq Ft Roof mounted solar array
    2014 Hydropool Serenity 5000 Hot Tub
    The Pool School- A great place to start
    Jason's Pool calculator

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •