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Thread: Problem keeping FC up (SWG trouble?)

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    Problem keeping FC up (SWG trouble?)

    Okay folks more trouble. It's been about 1 month since I properly shocked the pool and started testing the water properly. I am in fairly good balance (see number below). I am still having alot of trouble keeping my free chlorine up. I have been trying to dial in my SWG percentage to balance the loss from daytime sun.

    Just to give you some background, when we moved into the house last fall, I ran the pump 8 hours/day with the SWG at about 40-60%. This maintained the FC just fine. Since the winter (and into the Spring) it has been nothing but trouble. I am running the pump for 8 hours/day and the SWG is running 90%. I still lose FC to the tune of 4 PPM a day (although that varies a tad). After finding this site and reading, I assumed it was because all the water was out of balance and CC was high (and that was certainly a factor before I shocked). However, with the water now in balance I am stumped as to the cause. Is is bad cell?? ...

    Well, I took the SWG to the Pool store, they said it tested fine. I checked the voltage/amperage on both polarities - looks good (as far as I can tell). BTW - I have Hayward/Goldline Turbo Cell (T15)

    Here are the numbers if curious.
    FC 1.0 ppm
    CC 0.0 ppm
    pH 7.2
    CYA 65
    TA 70
    CH 200
    Salt 3300
    Temp 72F

    Incidentally, last Fall when the SWG was at 40% the pH, CYA, CH and TA were all in the same range.

    Any ideas? Help!!

    Todd
    ~18.5K gallon plaster - two level / spa to pool waterfall
    Pentair WhisperFlo WFE-28 Pump, Pentair Clean and Clear Filter
    Hayward Pool Vac Ultra Cleaner

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    Re: Problem keeping FC up (SWG trouble?)

    If you are losing 4ppm FC daily, that's not outrageous but probably indicates you have some organics in your pool.

    You are not keeping your FC nearly high enough with a CYA of 65, your FC should vary between3-5ppm but 1.0ppm is not enough

    Shut the SWG off in the evening and perform the OCLT (see Pool School)

    If you fail that test, you will need to shock the pool thoroughly (Pool School again)
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    JasonLion's Avatar
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    Re: Problem keeping FC up (SWG trouble?)

    You probably have a low level algae problem, enough algae to consume chlorine but not enough algae to be visible. I suggest raising to shock level and through brushing while at shock level until you pass an overnight FC loss test. Then, when algae is ruled out, raise the CYA level up to 80. Between those two steps you should be able to cut your chlorine consumption significantly.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Problem keeping FC up (SWG trouble?)

    I should have specified that the FC is NOT an overnight loss. I have been periodically checking the overnight loss. By periodically I mean once or twice a week. It has never been above 0.5 (mostly 0.0) since shocking 1 month ago.

    I went back into my spreadsheet and actually calculated the loss. My l4ppm number was a bit off. The actual daytime loss is is 2-3ppm.

    Todd
    ~18.5K gallon plaster - two level / spa to pool waterfall
    Pentair WhisperFlo WFE-28 Pump, Pentair Clean and Clear Filter
    Hayward Pool Vac Ultra Cleaner

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    Mod Squad jblizzle's Avatar
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    Re: Problem keeping FC up (SWG trouble?)

    2-3ppm seems pretty normal. But, since you have clearly not kept the FC level in the recommended range, there is a chance that something is trying to take hold. Get your FC up on the high end of the recommended range (using liquid chlorine) and keep it there ... may have to supplement with liquid occasionally if the SWG is not keeping up.

    Also, bumping the CYA up as Jason suggested may help as well.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Problem keeping FC up (SWG trouble?)

    Okay - your responses sound logical. But there are details I am leaving out. I should be thorough in my explanation...that is my fault.

    I have had trouble keeping the FC level up, but that dose not mean I have let it stay low. I have been supplementing the FC with Bleach to get the levels backup immediately upon testing.

    Also, the shock that was performed a month ago was a 12 day process that followed the book to the letter. Overnight chlorine tests were perfectly clean coming out of the test and since the test. This problem has been ongoing before the shock. But what is really telling is that was occurring immediately after it too.

    Listen, I hear you guys. It could be algae taking hold. Or maybe the shock never got rid of it all. I can certainly try another shock, but something seems weird.

    Thoughts,
    Todd
    ~18.5K gallon plaster - two level / spa to pool waterfall
    Pentair WhisperFlo WFE-28 Pump, Pentair Clean and Clear Filter
    Hayward Pool Vac Ultra Cleaner

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    Re: Problem keeping FC up (SWG trouble?)

    How does your water look?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Problem keeping FC up (SWG trouble?)

    Hi Dave,

    Crystal clear

    Todd
    ~18.5K gallon plaster - two level / spa to pool waterfall
    Pentair WhisperFlo WFE-28 Pump, Pentair Clean and Clear Filter
    Hayward Pool Vac Ultra Cleaner

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    Mod Squad jblizzle's Avatar
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    Re: Problem keeping FC up (SWG trouble?)

    I know you got the cell tested (I know nothing about how they do this ... are they more reliable testing the cells than testing our water ???).

    Out of curiosity, how old is the cell?
    What does the SWG think the salt level is?
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Problem keeping FC up (SWG trouble?)

    Great point Jason. I'll be honest, I don't trust the pool store that tested the SWG. They have steered me wrong before. The previous owners bought the pool in 06 and it is the original cell as far as I know. So it is 7 years old.

    The SWG says the salt is 3200 (test strip says 3300). Also the volt/amp output is +_26 V and +_6A give or take a few.

    I should note, that the cell was cleaned when it was tested.

    Todd
    ~18.5K gallon plaster - two level / spa to pool waterfall
    Pentair WhisperFlo WFE-28 Pump, Pentair Clean and Clear Filter
    Hayward Pool Vac Ultra Cleaner

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    Mod Squad jblizzle's Avatar
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    Re: Problem keeping FC up (SWG trouble?)

    Well, having the salt readings match is a good thing. It seems like when the cells start to go bad they start reading lower and lower salt levels. 7 years is actually pretty impressive as anecdotally (word???) they seem to last 3-5 years.

    When the cell is "generating", try taking a water sample from a return and you should find a significant FC level.

    How long ago was is cleaned and tested?
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    JasonLion's Avatar
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    Re: Problem keeping FC up (SWG trouble?)

    Those numbers strongly hint that the cell is good. When the cell is failing amps will be lower than that and the salt level will read significantly lower than actual.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  13. Back To Top    #13

    Re: Problem keeping FC up (SWG trouble?)

    The plot thickens. The cell was cleaned just before the shock (just over a month ago).

    Perhaps you guys were on the right track. Maybe the algae is still there.

    Frustrating...
    ~18.5K gallon plaster - two level / spa to pool waterfall
    Pentair WhisperFlo WFE-28 Pump, Pentair Clean and Clear Filter
    Hayward Pool Vac Ultra Cleaner

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    Re: Problem keeping FC up (SWG trouble?)

    Okay - here comes the part where I feel like a complete ***.

    I was just digging around on the message board and think I may have a handle on the problem. We have been periodically adding Ascorbic Acid. I knew that Chlorine ate AA, but didn't realise they eat each other.

    Question - if you dump in AA about how long can the effects of that linger (with respect to eating FC)....few days??

    Todd
    ~18.5K gallon plaster - two level / spa to pool waterfall
    Pentair WhisperFlo WFE-28 Pump, Pentair Clean and Clear Filter
    Hayward Pool Vac Ultra Cleaner

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    Mod Squad jblizzle's Avatar
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    Re: Problem keeping FC up (SWG trouble?)

    I think you are on to something there ... the ole Mutually Assured Destruction of AA and FC.

    Not sure how long the affects last, but I am sure is has something to do with the amount of AA you have added.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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  16. Back To Top    #16

    Re: Problem keeping FC up (SWG trouble?)

    In order for theory to be right the effect of AA would have to last for days. I went back and looked at my testing log and it seems when we add AA the drop in FC goes on for days afterward. That is, we add AA and FC drops the next day. I then add Bleach to raise it, then it goes back down on day 2...etc...etc.

    I am not 100% convinced that is the problem. However, it is the most likely option at this point. I will take a better stab at sequestering the metal and stop adding AA. Let's see if that works

    Todd
    ~18.5K gallon plaster - two level / spa to pool waterfall
    Pentair WhisperFlo WFE-28 Pump, Pentair Clean and Clear Filter
    Hayward Pool Vac Ultra Cleaner

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    maxepr1's Avatar
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    Re: Problem keeping FC up (SWG trouble?)

    Todd, take your water sample vial and collect water directly out of the return when the SWG is running. That way you be sure the generator is producing.
    40'x19' IG Diamond Brite 29K 4' Waterfall/Dive Rock FNS60 DE Inteliflo VS 2hp Whisperflo pumps Aqualogic(P4) SWG TF100 Tester


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    Re: Problem keeping FC up (SWG trouble?)

    I tried the return test. I took a hose from the return and measured the FC. It was 5ppm higher than the base pool level!!! I am guessing the SWG is not the issue. So I will move on from that theory.

    Have not added any additional AA in over 5 days. I am running the SWG for 8 hours at 90%. This is barely holding on to the FC level of 5ppm. Again, OCLT is showing no loss. CC levels are 0.0 to 0.5. CYA at 75 now.

    Given the high output of the cell, that still makes me think something is going on. Still can't get a handle on it.

    Here are the new numbers if curious.
    FC 5.0 ppm (10ppm at return with SWG on)
    CC 0.0 ppm
    pH 7.2
    CYA 75
    TA 70
    CH 200
    Salt 3300
    Temp 76F

    Todd
    ~18.5K gallon plaster - two level / spa to pool waterfall
    Pentair WhisperFlo WFE-28 Pump, Pentair Clean and Clear Filter
    Hayward Pool Vac Ultra Cleaner

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    Re: Problem keeping FC up (SWG trouble?)

    Todd,
    Did you ever get this issue under control? I think I may be having the same issue as you. I am going to have my cell tested today. If you got this resolved could you let me know what steps you took.
    Thanks,
    Sandy
    14X32 IG fiberglass, sand filter, salt system

  20. Back To Top    #20

    Re: Problem keeping FC up (SWG trouble?)

    Sandy,

    Yes. As best I could figure, the Ascorbic Acid effects on FC lasted about a week to two weeks. Slowly over time I began adding FC from the SWG as the AA wore off. I could then drop the percentage level on the SWG.

    I guess this is why they recommend adding FC back in slowly after an AA treatment. I certainly learned a lot in this process.

    Hope all goes well on your end.

    Todd
    ~18.5K gallon plaster - two level / spa to pool waterfall
    Pentair WhisperFlo WFE-28 Pump, Pentair Clean and Clear Filter
    Hayward Pool Vac Ultra Cleaner

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