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Thread: Staining and Sequestrant Questions

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    Staining and Sequestrant Questions

    Hi all. I have some staining on my pool built almost a year ago, so this was our first summer. I have some stains on the bottom of the pool and upon closer looking, I noticed the sides look different than the bottom. Determined that the stains disappear with Vitamin C (I was able to write "HI" with the tablet on one wall of the pool). I'm ready to buy the asorbic acid and complete the treatment. I don't know what is causing my stains. I had my fill water tested by my local pool store and the report said the iron and copper were barely out of range (I forgot to bring my results with me to work today so I could post those), and I looked at my water source's water quality report and I didn't see anything out of the ordinary. Are sequestrants the way to go as far as preventing stains in the future or do i just see what happens if I keep my PH on the low 7.2-7.4 side? If yes to sequestrants, I have these questions:

    1) What do I buy?
    2) How often would I use the sequestrant?
    3) Do I keep the sequestrant in over the winter? My pool is not covered so i test the ph and chlorine every week or so during the winter and adjust as needed.
    4) I read about sequestrants leaving behind phosphates so I would have to eventually treat for that. Is this correct? Isn't phosphate treatment a pain in the hiney?
    5) Anything else I should be aware of/be thinking about?

    Thank you for your help!
    Tricia
    22,700 gallon, 16x38 rectangular gunite pool with midnight blue quartz plaster, SWG (Intellichlor IC40), Pentair VS pump, Pentair Clean & Clear Plus cartridge filter, lakefront property

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    Mod Squad JVTrain's Avatar
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    Re: Staining and Sequestrant Questions

    Post those results when you have them for the fill water test.

    You can only get metals from fill water or from the products you use in the pool. Normally, once you clear the pool surface of stains, you continue to add a maintenance dose of sequestrant periodically to keep stains from recurring, especially if you know your fill water is the source of stains. If you do not close fully, yes you should continue sequestrants through the winter.

    Phosphates are largely irrelevant for pools. They can perhaps cause problems with SWG systems, but that takes high levels. Otherwise they are not an issue. You can by phosphate removers but that would only be needed if it was causing scaling on your SWG cell. Phosphates have no chemical effect on sanitation.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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    kcindc's Avatar
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    Re: Staining and Sequestrant Questions

    Here is a pool school article on metal staining and short description of the types of sequestrants: Pool School - Metals in the Water and Metal Stains

    Copper is present in many pool store algaecides and some forms of powdered chlorine particularly those with "blue" in the product name.
    Karen
    33K IG w spa plaster, Pentair 1HP Whisperflo, DE Filter, SWG CircuPool RJ-60, Dolphin Triton Plus, Raypak Dig 336K BTU, TF-100.
    Pool Math Chlorine / CYA Chart SLAM - Shock Level And Maintain
    2017 replaster/retile

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    hoskim's Avatar
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    Re: Staining and Sequestrant Questions

    I went through (and going through) the same issue. For "brown" (e.g.,), iron staining, I simply use ascorbic acid which I bought on eBay (~$50 for 10 lb). First two months (June, July), I used AA only once but since end-of-July, I find myself dumping AA almost every week (nothing changed / no refill). Using AA is "magical" as brown stains disappear quickly but I don't think they ever "go away." I also use Jack's Purple Stuff (following their recommendation on the label) and CuLator (1 bag a month). One thing I did (I don't think it helped much but will see), I took the light out of niche and cleaned out (had an unbelievable amount of algae, etc.) - make sure you have vacuum ready before you unscrew (I learned it the hard way). Also, I took all the screws out (including niche screws) and soaked them in vinegar / AA in order to remove some rust (did work rather well but soaked them for almost a week).
    25,000 Gal, in-ground w/ vinyl liner
    Hayward SP2303VSP (1.5 HP) / DE filter (4820)
    Aqua Rite SWG / T-CELL-9 (v1.5)
    Polaris 380, PB4-60 Booster Pump (post-2012) / Aqua Heat Pump (S95)
    TF-100 Test Kit with Speedstir

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    Re: Staining and Sequestrant Questions

    JVTrain --

    The fill water report said 0.3ppm copper (recommended range 0-0.2ppm) and iron 0.2ppm (recommended range 0-0.3ppm). That day I also took a pool water sample and the store's report said 0.1ppm copper and 0.2pm iron.

    I read all of the comments thus far and I searched and read some more on the forum about sequestrants and phosphates. I won't worry about phosphates -- I keep a check on my chlorine levels and CYA and keep those in the TPT recommended ranges, so phosphates shouldn't be an issue (I was concerned because my sis-in-law was told phosphates was causing her cloudy pool water last year and she did that floccing process. That being said, sis in law relies on pool store advice despite my repeated direction to this forum when she asks me questions, so I don't put much stock in her experiences.)

    I will order asorbic acid, polyquat 60, and a sequestrant -- I'm leaning towards the GLB Sequa Sol as it seems to be one of the least expensive and comes in gallons. Jack's is proud of their stuff! I will stock up on bleach and baking soda to have on hand to bring the pool chemicals back into range after the asorbic acid. Am I missing anything else?

    Thank you for your help. Again, this forum is a the bomb!
    22,700 gallon, 16x38 rectangular gunite pool with midnight blue quartz plaster, SWG (Intellichlor IC40), Pentair VS pump, Pentair Clean & Clear Plus cartridge filter, lakefront property

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    Mod Squad JVTrain's Avatar
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    Re: Staining and Sequestrant Questions

    That's on the border for metals staining for sure. You would be advised to use some sequestrant and keep an eye out for staining, watch your pH.

    Why stock up on baking soda? The only reason to use baking soda is if your TA drops below 60 ppm. If you're looking to have a product on hand to raise pH, borax is what you want. Typically sold under the 20 Mule Team brand name. It raises your pH without substantially increasing your TA.

    I have not had to use sequestrants myself, so I'll defer to others on the quality of the GLB product.

    Good to stock up on bleach, but don't buy more than a 6-8 week supply. Bleach does lose strength over time, so look for fresh bleach (check the date stamps on bottles), store in a cool, dark place and don't over do it on stocking up. I usually have 8-12 gallons on hand which is roughly 8 weeks for my large pool.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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    Re: Staining and Sequestrant Questions

    JVTrain -- thank you for the info. I will definitely purchase and use a sequestrant.

    I was thinking I read that the AA treatment lowers your TA and your pH, so that's why I was thinking baking soda. I will re-read and get enough borax to have on hand to raise the pH. I was planning to purchase enough bottles of bleach to raise my chlorine back up to recommended levels (and I'll check the pool calculator to determine how much to purchase).

    Am I right in thinking I will need to maintain my pH around 7-2 to 7.4 to help ward off staining?
    22,700 gallon, 16x38 rectangular gunite pool with midnight blue quartz plaster, SWG (Intellichlor IC40), Pentair VS pump, Pentair Clean & Clear Plus cartridge filter, lakefront property

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