Become a TFP Supporter Welcome to our new server and new forum software. Pool School
Results 1 to 13 of 13

Thread: what size cartridge filter and pump?

  1. #1
    Junior Member
    Join Date
    Jul 2009
    Location
    Northern CA
    Posts
    20

    what size cartridge filter and pump?

    I have a 20,000 gallon in ground pool. Currently have Hayward C900 cartridge filter (90 sq ft- 90 GPM) and a StaRite 3/4 pump. Both were installed by Leslies. I run my pool pump 7-8 hours a day in summer. A pool service came out to replace booster pump for my polaris and said my filter is way too small for my pool and that I should install a larger filter. My question is do I have the right size filter and pump for my pool? If I install a larger filter, won't I need a larger pump also?
    Jil
    20k gallon in ground pool w/spa, slide, diving board
    Polaris 280, Pentair 3/4 Booster Pump, Pentair 420 Cartiridge Filter , 3/4 Max E Glass Pump,
    Fafco Solar Panels, Pentair 300 Heater

  2. #2
    Senior Member
    Join Date
    Mar 2009
    Location
    Glendora, California
    Posts
    161

    Re: what size cartridge filter and pump?

    You do not need to upsize your pump if you upsize your filter. A larger filter will mean longer times between cleanings.
    18k Inground Plaster pool / TriStar Variable Speed Pump and Controller
    48sq ft Hayward DE filter/ Swim pure Plus 40k cell / Kreepy Krauly
    Solaxx Ph-Tek

  3. #3
    Senior Member In the Industry

    Join Date
    Apr 2007
    Location
    Raleigh, NC
    Posts
    21,554

    Re: what size cartridge filter and pump?

    Both pump and filter are a good match for each other and are the right size for your pool.

    Filters can always be bigger but yours is adequate. If you decide to go larger anyway, the pump is still a good match for your pool.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
    TFTestkits owner
    TFTestkits , PoolMath , Pool School

  4. #4
    Junior Member
    Join Date
    Jul 2009
    Location
    Northern CA
    Posts
    20

    Re: what size cartridge filter and pump?

    The pool service is recommending I install Pentair 420-which is a huge jump in size from my current filter.
    What would be the advantage for installing a larger filter?
    Jil
    20k gallon in ground pool w/spa, slide, diving board
    Polaris 280, Pentair 3/4 Booster Pump, Pentair 420 Cartiridge Filter , 3/4 Max E Glass Pump,
    Fafco Solar Panels, Pentair 300 Heater

  5. #5
    Senior Member In the Industry

    Join Date
    Apr 2007
    Location
    Raleigh, NC
    Posts
    21,554

    Re: what size cartridge filter and pump?

    What would be the advantage for installing a larger filter?
    Generally, a more effective system. you would not have to clean as often because of the increased capacity and it would filter out more dirt.

    That said, not enough of a difference that I would change it, in your case.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
    TFTestkits owner
    TFTestkits , PoolMath , Pool School

  6. #6
    Senior Member mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    6,245

    Re: what size cartridge filter and pump?

    I'm a bit surprised that they would put a 90sq-ft filter on a 20k pool. I have about the same size pool and I have a 420 sq-ft filter. What is also odd is that Hayward rates that filter at 90 GPM when some would rate that size filter at about 30-35 GPM.

    The problem I see is that first, you will be cleaning it fairly often, probably more than once per month. I clean mine twice a year. Second, the flow rate on the pump will probably shorten the life of the cartridge.

    This seems to me to be a mistake by Leslies and they should swap it out for no charge and credit the cost of the filter. If they are not willing to do that, then I would say live with it but I would try and get them to do the right thing.

    [EDIT] It seems that most manufactures are using the NSF flow rates standards for residential cartridge filters at 1 GPM/sq-ft which seems quite high to me. The NSF standard for a public pool is 0.375 GPM/Sq-Ft which seems more reasonable to me and closer to design rates recommended by others. Personally I would use the lower public pool spec.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

  7. #7
    Junior Member
    Join Date
    Jul 2009
    Location
    Northern CA
    Posts
    20

    Re: what size cartridge filter and pump?

    I clean my Hayward 90 sq ft. cartridge about once a month from late spring, summer, and fall-(per Leslies instructions.) In winter I try and slide 3-4 months and only run pump 3 hours a day. I am constantly struggling with algae and wonder now if it is because of filter. Never had problem when we had the DE filter.
    I doubt Leslies would replace my filter, if Hayward rates the 90 sq ft filter at 90GPM, it would be hard to prove I have wrong size filter. I have had the cartridge filter about 4 years.

    I am about to replace my very old gas heater before it rust completes out (rarely use it for the spa that is attached to in ground pool-have solar on roof for pool) and don't want to add the added expense of a new 420 cartridge filter at $730 But the thought of only cleaning cartridge 2 times a year is tempting, if it eliminates my algae problem then I would be really tempted to spend the added expense.

    Is the 420 cartridge filter the ideal size for my 20k size pool? What about 320? or 240?
    Jil
    20k gallon in ground pool w/spa, slide, diving board
    Polaris 280, Pentair 3/4 Booster Pump, Pentair 420 Cartiridge Filter , 3/4 Max E Glass Pump,
    Fafco Solar Panels, Pentair 300 Heater

  8. #8
    Senior Member mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    6,245

    Re: what size cartridge filter and pump?

    I'm not sure a larger filter would solve the algae problem. Usually that is caused by CYA too high or chlorine too low. What CYA level are you running and what do you use to chlorinate the pool?

    I didn't realize that you had the filter for 4 years already. I would just stick with it unless you really hate to clean it (one of the reasons I went with a larger filter).

    There really is no ideal size for a filter although there certainly is a size which is too small. A 420 sq-ft filter is probably boarderline overkill but I barely have a 1 PSI rise when I clean it so I am pretty happy with the choice. However, the minimum I would go with is something which meets the flow rate requirements of the pump. A 3/4 HP Sta-Rite (MaxEPro?) might have at best 70 GPM on decent plumbing. So yes, I think you could get away with a 320 or 240 and probably still stay with a twice a year schedule. But I don't think it is necessary to replace it right now. You might as well get your moneys worth out of it.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

  9. #9
    Junior Member
    Join Date
    Jul 2009
    Location
    Northern CA
    Posts
    20

    Re: what size cartridge filter and pump?

    well, I am getting educated on pool maintenace at this website. I use 3" tabs and after reading, will change to liguid bleach from Costco. Not sure what Cya level is right now. Last year it was high and we drained 3/4 of our pool. I just ordered the a new TFP test kit and then will be able to test cya level without going into Leslies!!

    For now we are planning on keeping filter and replace the old heater and update the timers and valves.

    Thanks for help.
    Jil
    20k gallon in ground pool w/spa, slide, diving board
    Polaris 280, Pentair 3/4 Booster Pump, Pentair 420 Cartiridge Filter , 3/4 Max E Glass Pump,
    Fafco Solar Panels, Pentair 300 Heater

  10. #10
    Senior Member mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    6,245

    Re: what size cartridge filter and pump?

    Sounds like a good plan.

    CYA can build up pretty fast with a Tri-chlor puck/cartridge filter combo. Since there is no backwashing with a cartridge filter, CYA keeps building up until algae shows up.

    Once you go to BBB, you will probably find the pool much easier to maintain.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

  11. #11
    Senior Member In the Industry

    Join Date
    Apr 2007
    Location
    Raleigh, NC
    Posts
    21,554

    Re: what size cartridge filter and pump?

    A couple of points.....

    If it's about pumps, listen to Mark's advice. His expertise is a real benefit to all of us on the forum.

    Secondly, If you have algae, there is no filter available that will cure that. You have unbalanced pool water......most likely too much CYA and certainly not enough chlorine.

    Post your numbers up as soon as you get the test kit (thank's for your business!) and you'll get a lot of great help here getting your pool crystal clear and keeping it that way.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
    TFTestkits owner
    TFTestkits , PoolMath , Pool School

  12. #12
    Junior Member
    Join Date
    Jul 2009
    Location
    Northern CA
    Posts
    20

    Re: what size cartridge filter and pump?

    I bought a Pentair 420 last fall. Best investment I ever made. I just cleaned the filter after 6 months of running (it could of went longer). My pool has never stayed this clean before. No more cleaning the small cartridge every month.
    Jil
    20k gallon in ground pool w/spa, slide, diving board
    Polaris 280, Pentair 3/4 Booster Pump, Pentair 420 Cartiridge Filter , 3/4 Max E Glass Pump,
    Fafco Solar Panels, Pentair 300 Heater

  13. #13
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Location
    Tucson, AZ
    Posts
    20,584

    Re: what size cartridge filter and pump?

    Glad to see you report back

    I would imagine you could get away with only cleaning it once per year. {Our typical recommendation would be around 300 sqft, so you are certainly over that!} We are also now recommending cleaning the filter when the pressure goes up 20-25% of the clean pressure. So make a note of you current pressure and you will then know when you should clean it again.
    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, Dolphin Diagnostic Robotic Cleaner, TF-100 test kit w/ SpeedStir
    Gone: Hayward RS1500 pump, undersized DIY solar heater, Dolphin Dynamic Robotic Cleaner
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

Posting Permissions

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