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Thread: pool walls turned grey

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    pool walls turned grey

    Have a customer who had really low ph and alkalinity in his 18 x 36 in ground pool. Never added and sodium bicarb in years. He went through many pumps over the years. Well I had him add 40 lbs of bicarb. He says a day later his entire pool liner and steps turned grey and will not come off by brushing. What could this be? He thinks it because I had him add the bicarb. But I dont see why that would do it to the liner. HELP!!!
    Jessica (first time pool owner)
    NE Texas
    Intex Ultra Frame UG 12x24x52; 8,500 gallons
    Intex 1600 Sand Filter (SF15110)
    Intex Saltwater System (CS8110)

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    Re: pool walls turned grey

    Do you have a full set of reliable test results? You mention liner, is it vinyl?
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    Re: pool walls turned grey

    I would suspect copper stains. Is there a heater? Are there any turquoise colored stains?

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    Mod Squad jblizzle's Avatar
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    Re: pool walls turned grey

    Is that the correct signature for you? Do you own a pool business or something?

    Why did you add 40pounds of bicarb? What was the TA before? What were your trying to accomplish?

    Assuming the pool is about 18k gallon, 40 pounds of baking soda would raise the TA by 159ppm (which is crazy since our recommended ranges are 70-90ppm or so, maybe 120ppm if they use trichlor pucks) and the pH by 0.3.

    Anyway the only thing I can think of is that adding all this raised the pH enough for metal staining to occur.
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    Re: pool walls turned grey

    I would suspect that the pool was operated on tabs for a while. If that's the case, it's quite possible that the TA was below zero. The low pH would eat a copper heat exchanger and raise the copper level quite a bit. Copper algaecide would also add to the copper level. The low pH would help prevent copper stains. The bicarb would bring the pH from somewhere below 4.5 up to the 7 + range. If the pool was simultaneously shocked or had a high chlorine level, the risk of staining would be increased.

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    Mod Squad jblizzle's Avatar
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    Re: pool walls turned grey

    Very plausible ... the 40 pounds of baking soda seems a bit like acting blind though.
    Jason, TFP Moderator
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    Re: pool walls turned grey

    Agreed. We would need further information to better assess what's going on here. If the sample turned red immediately, then the TA is zero or lower. There is a way to determine how negative the TA is, but I don't know if the OP determined the TA.

    If the TA were below zero, then 40 pounds might be reasonable. However, in that case I would suspect that the cyanuric acid level was very high. In that case, a partial drain and refill would probably be in order.

    We'll need further details from the OP.

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    Re: pool walls turned grey

    If you in fact did raise his ph over 8 its possible metal stains are the result...if you didn't know what his ph was, you have no way of really knowing how much to add...I am all for the sneak up on it method, especially with any customer, unless you are using TFP or Taylor Test Kits, you have no way of knowing what the yellow really means for the PH, other then it is low, but how low really. Base demand would give you an idea of where it really is, then you could slowly work your way up, dumping that much at one time can cause many many issues. I always divide dosages by half or a third and broadcast over pool over several hours so you can see what the results are, rather then wham, and oops, sorry, now you need to buy several tons of dry acid Get a TFP kit, you will never regret that purchase.

    Weird thing is, customers with really low Ph, most have clear pools, I tell them with a smile, yep, algae rarely appreciates a good acid bath

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    Re: pool walls turned grey

    i'm confused, in jessica's first ever tfp post http://www.troublefreepool.com/threa...163#post539163 she said
    My pool is cloudy and will not clear it is 18 x 36 inground about 27000 gallons. I threw in 3 pounds of cal hypo and didnt get a reading so today i dumped in 8 gallons of liquid chlorine
    . Her sig says above ground 8500 gallons, now her customer has a 18 x 36 inground? It sounds like she likes dumping large quantities of chemicals in the pool.
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    Mod Squad jblizzle's Avatar
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    Re: pool walls turned grey

    I agree with you poolnoob ... very confused at this point.

    One thing is clear ... they have not grasped the fundemental mantra of TFP:
    Understanding your pool’s chemistry through accurate testing, and adding only what the pool NEEDS.
    Jason, TFP Moderator
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    Re: pool walls turned grey

    Im sorry for all the confusion guys. I work at a pool store in minnesota. I cant figure out how to edit my signature. The customer had 0 TA we test on the water link spin disk system. He has had a very low PH and TA All season im guessing because when he finally came in he said he hasnt added one thing to his pool all season long and has never had a problem. Wich im guessing because its so acidic algae wont even grow in it. I had him add 40 lbs of TA in 2 seperate doses. I came to conclusion that his heat exchanger has been eaten up with the acidic water and once I brought the PH and TA up the metals stained the water. So would something like sequa sal or stain n scale remove the stains or do we need to add acid back in to get stains off? Again sorry for confusion I was at work and had to be quick. Any other info you guys need let mew know thanks again

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    Mod Squad jblizzle's Avatar
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    Re: pool walls turned grey

    Sounds like they need to do an Ascorbic Acid treatment. There is a link to the process and the chemicals we recommend in Pool School: http://www.troublefreepool.com/conte...d-metal-stains

    After the AA treatment, they will need to continually use sequestrants.
    Jason, TFP Moderator
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    Re: pool walls turned grey

    Just an FYI, spin disk is rarely accurate, check its results on a number of pools with actual drop tests, you will be shocked at the result.

    Agree with Jason, AA is needed and then an attempt to remove the metals.

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    Re: pool walls turned grey

    What are the current pH, TA and CYA?

    Have you tested for copper?

    Are there any other stains? Turquoise, green, purple etc.?

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