Become a TFP Supporter Pool Math Forum Rules Pool School
Page 1 of 2 12 LastLast
Results 1 to 20 of 21

Thread: Filter Sizing

  1. Back To Top    #1

    Join Date
    Sep 2011
    Location
    Omaha, NE
    Posts
    95

    Filter Sizing

    I went and bought a new sand filter without looking up what I should have really gotten. I bought a 100# filter. With my previous filter and now with this one, I keep getting fine silt on bottom of pool. I assume it is coming from filter, since while I vacuum and the pump is on high, i see it slowly collecting again behind me. If I have my pump on low speed, accumulation is alot slower. I have a 2-speed 3/4 to 1Hp pump. Today, the pump had been on low speed and I kicked it up to high speed, and a cloud of dirt came out of return. There is brand new sand in filter too.
    Am I just filling my filter up too quick and just need to backwash more ofter? Did I buy too small filter? My pressure never increased with all the silt in filter.... Pool is about 10,000 gallons
    16X24 Oval Doughboy
    10,000 Gallons~
    Pentair Dynamo .75/1.0 HP pump
    16" Pooline D-400 Sand Filter w/ 6-way valve

  2. Back To Top    #2
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Location
    Tucson, AZ
    Posts
    37,389

    Re: Filter Sizing

    Filter sizing is usually just based on the pool volume. For your size pool, I would suggest a minimum of 18" diameter (larger being better) ... not sure how that equates to # of sand.

    Which pump do you have? Add more info to your signature.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  3. Back To Top    #3

    Join Date
    Sep 2011
    Location
    Omaha, NE
    Posts
    95

    Re: Filter Sizing

    How does one measure that 18" diameter? The center of filter its self? It is a Pentair Dynamo pump
    16X24 Oval Doughboy
    10,000 Gallons~
    Pentair Dynamo .75/1.0 HP pump
    16" Pooline D-400 Sand Filter w/ 6-way valve

  4. Back To Top    #4
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Location
    Tucson, AZ
    Posts
    37,389

    Re: Filter Sizing

    Across the widest part of the filter.

    What model filter? Add that to your signature too.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  5. Back To Top    #5
    Mod Squad JVTrain's Avatar
    Join Date
    Feb 2014
    Location
    Central Minnesota
    Posts
    5,079

    Re: Filter Sizing

    Quote Originally Posted by jblizzle View Post
    Across the widest part of the filter.

    What model filter? Add that to your signature too.
    I was going to make fritz measure the circumference and divide by pi, but that works too.

    What type of sand did you fill the filter with? Brand and sizing? 16" filters are 100 pounds, 18" filters are about 150 pounds of sand while at 24" is about 300 pounds of sand.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

  6. Back To Top    #6

    Join Date
    Sep 2011
    Location
    Omaha, NE
    Posts
    95

    Re: Filter Sizing

    It is a Pooline D-400. the 400 is the diameter, I assume it is metric.
    16X24 Oval Doughboy
    10,000 Gallons~
    Pentair Dynamo .75/1.0 HP pump
    16" Pooline D-400 Sand Filter w/ 6-way valve

  7. Back To Top    #7

    Join Date
    Sep 2011
    Location
    Omaha, NE
    Posts
    95

    Re: Filter Sizing

    Could I just add DE to top of sand to catch the fine silt?
    16X24 Oval Doughboy
    10,000 Gallons~
    Pentair Dynamo .75/1.0 HP pump
    16" Pooline D-400 Sand Filter w/ 6-way valve

  8. Back To Top    #8
    Mod Squad JVTrain's Avatar
    Join Date
    Feb 2014
    Location
    Central Minnesota
    Posts
    5,079

    Re: Filter Sizing

    If the fine silt is coming through, so will the DE. That's why I asked about the sand type you used. Some brands of sand have had known issues in the past with being improperly sized for pool filtration.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

  9. Back To Top    #9

    Join Date
    Sep 2011
    Location
    Omaha, NE
    Posts
    95

    Re: Filter Sizing

    I threw the bags away already, but I saw that they were #20 quartz. I would have to call pool store for brand and they are out of them right now to look at bag. I think my diameter is too small, it is a 16".
    16X24 Oval Doughboy
    10,000 Gallons~
    Pentair Dynamo .75/1.0 HP pump
    16" Pooline D-400 Sand Filter w/ 6-way valve

  10. Back To Top    #10
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Location
    Tucson, AZ
    Posts
    37,389

    Re: Filter Sizing

    Generally that would just mean more frequent cleanings. I would not think that your Dynamo would be able to blow the dust through the filter.

    Did you backwash the sand to clean it before using it?
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  11. Back To Top    #11

    TFP Guide
    PAGirl's Avatar
    Join Date
    Jun 2012
    Location
    Central PA
    Posts
    2,388

    Re: Filter Sizing

    Are you sure it's not algae? What is your CYA and FC? Have you tried an OCLT? In the past, before TFP, I had what I thought was sand, and it turned out to be small amounts of algae.
    26' X 52" Intex Ultra Frame. Intex Sand Filter
    26' X 52 Intex Ultra Frame Install
    You can lead a horse to (clear) water, but you can't force him to swim in it!

  12. Back To Top    #12
    mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    11,482

    Re: Filter Sizing

    Was it dirt, dead algae or sand that came out?

    Sand could indicate a broken lateral.

    Also, many sand filters have a problem with dead algae being too small to filter out so we usually recommend adding a little DE to the sand to filter that out, then backwash.
    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

  13. Back To Top    #13

    Join Date
    Sep 2011
    Location
    Omaha, NE
    Posts
    95

    Re: Filter Sizing

    I have not checked my numbers in about 1 week, but when I opened it up from winter, all numbers were good. I did backwash new sand. I will have to recheck numbers and post again tomorrow, esp the OCLT. It makes a cloud when I brush it, too cold to get in and see if it is sand (temp is 60). Also, not sure if it means anything, but my pressure on the filter in only at 14psi when on high and 4psi when on low.
    16X24 Oval Doughboy
    10,000 Gallons~
    Pentair Dynamo .75/1.0 HP pump
    16" Pooline D-400 Sand Filter w/ 6-way valve

  14. Back To Top    #14

    Join Date
    Sep 2011
    Location
    Omaha, NE
    Posts
    95

    Re: Filter Sizing

    The sand I was using is Fairmont

    Amazon.com : Pool Filter Sand #20 Grade Silica Sand - 50 lbs. : Patio, Lawn Garden


    Tonights numbers

    FC - 2.5
    CC - 0
    PH - 8.1
    CYA - 25ish
    Temp 56.256987

    Will post OCLT tomorrow

    Just need to get my PH down too, alot of rain here recently
    16X24 Oval Doughboy
    10,000 Gallons~
    Pentair Dynamo .75/1.0 HP pump
    16" Pooline D-400 Sand Filter w/ 6-way valve

  15. Back To Top    #15

    Join Date
    Sep 2011
    Location
    Omaha, NE
    Posts
    95

    Re: Filter Sizing

    OCLT was 0

    I figured out my problem, just not sure the "why's" of it. The same thing happened to me with my last filter, thought this new filter would take care of it. Thought of it last night and gave it a try and it worked.

    For some reason, my return eye diverter needs to be left off when in high speed. Whatever physics or science is behind it, not sure. The pressure is backbuilding enough in the filter that it is allowing the fine silt to work its way thru??? Any physics gurus have any ideas?

    I have a Doughboy pool and whatever size opening they have must be too small. Will have to measure it someday when the water is warmer.....

    Thanks to everyone for their help and input with me!! I always love this site and have converted 2 people so far!!
    16X24 Oval Doughboy
    10,000 Gallons~
    Pentair Dynamo .75/1.0 HP pump
    16" Pooline D-400 Sand Filter w/ 6-way valve

  16. Back To Top    #16
    mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    11,482

    Re: Filter Sizing

    As I said before, it could be dead algae. It is so small that on high speed it makes it's way through the filters.

    Does the filter pressure go up when you move the eyeball? It could be that when you turn the eyeball, it slows flow enough so the debris doesn't make it through the filter.
    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

  17. Back To Top    #17

    Join Date
    Sep 2011
    Location
    Omaha, NE
    Posts
    95

    Re: Filter Sizing

    If I take the eye off and have it just open all the way, nothing screwed on there, the pressure drops from 14 to 10. And no silt form on the bottom of pool....
    16X24 Oval Doughboy
    10,000 Gallons~
    Pentair Dynamo .75/1.0 HP pump
    16" Pooline D-400 Sand Filter w/ 6-way valve

  18. Back To Top    #18
    mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    11,482

    Re: Filter Sizing

    That is the opposite of what I would expect. The lower pressure, which is expected, is due to the reduced head loss of removing the eyeball but that should result in higher flow rate and more dust being blown back into the pool, not less.

    It could be that there still is dust being blown out but since you aren't pointing at the floor, it doesn't collect as quickly. Turn off the pump for a couple of hours and see if it settles out.
    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

  19. Back To Top    #19

    Join Date
    Sep 2011
    Location
    Omaha, NE
    Posts
    95

    Re: Filter Sizing

    Turned off pump for 2 hours and no dust settled at bottom of pool. It is that dam eyeball messing things up!!!
    16X24 Oval Doughboy
    10,000 Gallons~
    Pentair Dynamo .75/1.0 HP pump
    16" Pooline D-400 Sand Filter w/ 6-way valve

  20. Back To Top    #20
    mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    11,482

    Re: Filter Sizing

    It could be a problem with the filter and under higher flow, it seals the gap while under low flow it allows the debris through. It might be worth while to take apart the filter to make sure you don't have any broken laterals or perhaps a broken multi-port.
    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

Page 1 of 2 12 LastLast

Posting Permissions

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