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Thread: High PH and Filter Cartridges

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    High PH and Filter Cartridges


    I have a 10,000 gl. above ground, and have had trouble with the water flow through my cartridges becoming restricted. I get a new cartridge and within a few weeks I go from 11-12 lbs. on the gauge, to 18-19...and with no "visible" debris on cartridge. I can take it out and hose it off, and it'll go down to about 14lbs., but will be right back up to around 18-19 lbs. about an hour later. And of course at that pressure there's very poor circulation.

    I've also recently discovered I wasn't accurately testing my ph levels. Now I am thanks to recommendations I've received on this site, and I found out my ph levels have been at least 8 or above. Been struggling to keep chlorine levels up as well. My water is clear but I've been adding chlorine like crazy!

    I've got the ph down now to between 7.4 and 7.8. Could the restrictions in my cartridge be tied to the chronic alkaline water I had? Thanks for your time



  2. Back To Top    #2

    TFP Guide
    Jimrahbe's Avatar
    Join Date
    Jul 2014
    Bedford, TX

    Re: High PH and Filter Cartridges


    Well, the good news is that your cartridges are working just fine. The bad news is that your cartridges have something to work with....

    90% of the time (I just made up that number) what you are experiencing is algae.. Clean cartridges work fine, but after a few hours of collecting dead algae, they can no longer pass water easily, and the pressure goes up. This has nothing to do with pH.

    The fact that you are having to add chlorine "Like Crazy", is just another indication of a possible algae outbreak.

    How are you testing your pool water? Please post the following test results:


    These number are all interrelated, so they are all important in any advice we can provide.


    Jim R.
    Finished in 2015 - 17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4, IC40 SWG, 3 HP VS Pump, CCP5200 Cartridge Filter.
    TF100 with SpeedStir and SampleSizer, ColorQ Pro 7, Dolphin Premier Robot Cleaner, added Screen Logic 2.

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    Re: High PH and Filter Cartridges

    Ok I will post the numbers as soon as I get them

  4. Back To Top    #4

    Re: High PH and Filter Cartridges


    Here are my results…

    Hardness-150 or 500

    Sorry about the last 2 values! The hardness reading of 150 came from my tft testkit, BUT my reagents are a couple of years old. The 500 came from a test strip. The strip also showed a 30-50 reading on the CYA, but the test kit indicated none, as I could easily see bottom of test tube after filling…no cloudiness at all.

    I used 3” pucks for years and then discovered my CYA was off the charts. So I drained of the water and have been using nothing but liquid chlorine every since.

    I really don’t think my issue is algae, at least none that I can see. When I rinse the cartridge there’s no green. It’s just a sandy tan color, and my water is clear. So I’m not sure what’s happening to my cartridges after a few weeks with rising pressure? I thought maybe the high alkalinity was causing scaling to clog it? If not, then I’m stumped. Thanks

  5. Back To Top    #5

    Join Date
    Feb 2009
    Paradise (Hampstead, NC)

    Re: High PH and Filter Cartridges

    That sandy tan color is likely dead algae. Do an OCLT :Pool School - SLAM - Shock Level And Maintain. Algae doesn't show up until it is at almost catastrophic levels...then it quickly becomes a catastrophe. Remember the motto: "MORE BLEACH!"
    16X32 AB, Jacuzzi Laser 190 19" sand filter, 3/4hp Pentair Optiflo, CircuPool RJ30+ swg, TF 100

  6. Back To Top    #6
    mas985's Avatar
    Join Date
    May 2007
    Pleasanton, CA

    Re: High PH and Filter Cartridges

    Also, bring your CYA up to at least 30 ppm so you can read it on the test. Without CYA, the FC will not last long during the day which can be part of your problem.
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner

  7. Back To Top    #7

    Re: High PH and Filter Cartridges

    Thanks everyone! I'm going to employ your advice and report back.

    You guys are great.


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