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Thread: Pentair cartridge filter rusting inside

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    Pentair cartridge filter rusting inside

    Hello, I have some issues with rust inside my cartridge filter. See pictures.





    Some background:
    Pool is about 3 years old. Located in a Houston suburb
    SWG
    ~25,000 gallons
    Using BBB from the beginning. Never had an algae

    Here are my typical chemistry ranges:
    PH is 7.6 - 8.0+
    I am out of town during the week, so typically all maintenance is happening on weekend. Typically I add 1/2 to 1 gallon of acid every week. PH is back in 8.0 range every week

    TA 40-70
    When TA gets down to 40 I typically bump it up with baking soda

    Salt 2950-3300
    Salt level varies depending on the amount of rain we get. Typically when it drops below 3000 I add 2-3 50lb bags of salt

    CH 290-330
    Gets lower with rain but then trending higher with fill water

    I wonder if these swings in PH (due to weekly maintenance cycle) can cause such rusting. I wonder if I need to get an acid feeder.
    I have noticed rust about a year ago. It is getting worse.

    Any thoughts? Suggestions?
    NW Houston: 25K gunite pool & spa and pebble finish. Travertine deck.
    Pentair pumps: VS (pool); 2HP & 1.5HP (water features); booster pump
    400K gas heater; 520 cartridge filter; IntelliTouch + 8 function wireless

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    JoyfulNoise's Avatar
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    May 2015
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    Pentair cartridge filter rusting inside

    Bar Keepers Friend works great at removing rust stains.



    It contains oxalic acid so you MUST rinse out the filter really well after use.





    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    cowboycasey's Avatar
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    Re: Pentair cartridge filter rusting inside

    I dont think it has anything to do with a high PH, maybe a low PH would but you say it always raises.. It probably has more to do with the salt water than anything.. with a SWG pool this is what happens, it will take life of the motor, filter or anything else that has metal... how much life is hard to know.. that filter may last the next 15 years, there is no real way to know for sure...
    Pool: Intex 16x32 15000 gal, 2 speed 340042, Pentair CC320 Filter, CircuPool SJ45 Salt System, Intermatic PE653RC; Hot Tub: 650 Gal SWG Megachlor
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    Re: Pentair cartridge filter rusting inside

    Thank you for your input. I will try to clean it with Bar Keepers Friend.
    My bigger worry in not the life of equipment but rather iron stains in the pool.

    I wonder if rusting of the equipment is common with SWG or if I have messed up something.
    NW Houston: 25K gunite pool & spa and pebble finish. Travertine deck.
    Pentair pumps: VS (pool); 2HP & 1.5HP (water features); booster pump
    400K gas heater; 520 cartridge filter; IntelliTouch + 8 function wireless

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    pabeader's Avatar
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    May 2015
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    Re: Pentair cartridge filter rusting inside

    I will have to take another look at mine. I have the same model, and a SWG. I think I remember seeing rust in the same places. I just assumed it was from all the metals I have in my water. Will report in the morning if I get a chance to look before work.
    Bob - Palm Beach by San Juan Pools. approx 5000 gals., Pentair 320 cartridge filter (all new guts installed by me), Goldline SWG, 'New to me' Kreepy Krauly Sand Shark, Intermec 104 Timer Test kit: TF-100 w/Speed Stir

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    Join Date
    Aug 2015
    Location
    Friendswood, TX
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    9

    Re: Pentair cartridge filter rusting inside

    I opened my Pentair filter after a year in service and it looked very similar. I also have a SWCG and have trouble controlling the pH (it goes high). I have an acid addition system but can't get enough acid added to maintain pH below 8.0 without manual acid addition. With all that said, I think it's just cheap Pentair parts. The band is stainless steel so I wouldn't expect to see rust regardless of the pH or salt content. I'm not sure how the band is fastened to the fiberglass container but there's obviously some non-stainless steel parts metal behind the band that are rusting that would be worse with salt and pH excursions...
    20,000 gallon plaster pool with spa, built in 2005
    Pentair IC40 SWCG with Pentair IntellipH acid addition
    Polaris 360 cleaner, Pentair 520sf cartridge filter
    Borate added

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