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Thread: Can't maintain FC with SWG

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    Can't maintain FC with SWG

    This is my first post but I have been visiting the board for a while. I just filled this pool for the first time in January. Since the pool has warmed up to above 80 degrees I have been having trouble keeping FC above 1 ppm with my SWG. I have been running the pump at least 14 hours/day with the setting on the SWG at 80 out of a possible 100. I finally decided to add liquid chlorine yesterday. I turned off the SWG and started adding 10% liquid chlorine yesterday about noon. By dark (8:30 pm) I had added 1 gallon of liquid chlorine and the FC was only 4.5 ppm. I shut everything down and tested the FC this morning and it had dropped to 2.5 ppm. It appears I just need to shock the pool, but I wanted to make sure I wasn't missing something before I took the FC to 21 ppm. My test results from yesterday before adding the liquid chlorine were:

    FC: 1.0, TC: 1.5, PH: 7.4, TA: 80, CYA: 60-70, Borates: 45 ppm, CH: 350, Salt: 3300 ppm.

    Thanks for your help
    6800 gal fiberglass pool w/300 gal spillover spa, shared 1.5 HP pump and 150 sq ft sta-rite cartridge filter. Goldline PS-8 automation and SWG.

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    frustratedpoolmom's Avatar
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    Re: Can't maintain FC with SWG

    That sounds like a plan. Raise it to shock level again tonight and repeat the overnight test. If your water is clear, it shouldn't take too long shocking to correct the issue. Other than chlorine the numbers look good. If you want to tweak it, raise the CYA to 70-80.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: Can't maintain FC with SWG

    Hey, Dougster,

    Welcome to the forum. I don't see anything you're missing. It sure sounds like you've got some organics cooking in your pool and you need to shock to eliminate them.

    I wouldn't hesiate to calculate a dosage up around 25ppm and then (here's the key to this process) hold the 25ppm there constantly by adding chlorine until your overnite FC loss stops.

    We're working on an overnight FC loss article in Pool School so, if it's not clear how to do it, post back.

    The shocking process will be finished when....
    1. Your pool water is sparkling
    2. Your CC's are .5ppm or less
    3. You can hold your FC overnight without losing more than 1ppm.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Can't maintain FC with SWG

    Thanks for all the input.

    I found the source of my organics. The pool builder had put a cannister type filter with a clear plastic cover on the auto water fill line. I pulled the cartridge filter out and it was covered with green algae. So I was apparently introducing algae into my pool through the auto fill line. I threw the cartridge away and filled the cannister with a mixture of bleach and water to kill all the algae. I closed the valve on the auto fill and will be replacing that section of line with 3/4" PVC this weekend, so that should eliminate the source. I have taken the covers off the lights in the pool and brushed the lights down.

    The last two nights I have raised the FC level to 25 only to find it at 15 yesterday morning and at 18 this morning. It is a slow process but it seems that I am making headway. The water remains clear with no apparent signs of algae, I just keep losing FC. Hopefully one more day will do it.
    6800 gal fiberglass pool w/300 gal spillover spa, shared 1.5 HP pump and 150 sq ft sta-rite cartridge filter. Goldline PS-8 automation and SWG.

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    frustratedpoolmom's Avatar
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    Re: Can't maintain FC with SWG

    Thanks for the update.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: Can't maintain FC with SWG

    This is a really late update, but I think it is worth posting as it may save someone some money. I finally found the real reason that I couldn't keep the FC up with my SWG. I live in west Texas where the water is really hard and has a pretty high calcium content. The SWG kept forming calcium carbonate scale on the grids where the chlorine is generated. As soon as the scale formed the FC in the pool would drop. I have since switched to bleach and or chlorine tabs. Just a tip to be sure and verify that water in the area in which you live is compatible with a chlorine generator before you spend the cash on one.
    6800 gal fiberglass pool w/300 gal spillover spa, shared 1.5 HP pump and 150 sq ft sta-rite cartridge filter. Goldline PS-8 automation and SWG.

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    linen's Avatar
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    Re: Can't maintain FC with SWG

    Dougster5000, I know this is too late for you, but most swg users, even in with high CH water should be able to control the scaling on the swg plates by keeping TA and ph a little lower. My CH out of my well runs above 300 ppm and I have not had to clean my cell the last two years.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: Can't maintain FC with SWG

    And by using 50 ppm Borates which cuts the amount of pH rise in the salt cell in half.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    linen's Avatar
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    Re: Can't maintain FC with SWG

    Quote Originally Posted by chem geek
    And by using 50 ppm Borates which cuts the amount of pH rise in the salt cell in half.
    Good point CG, I too have Borates at 50 ppm!
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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