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Thread: Just started No Drain Acid Wash

  1. #1
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    Just started No Drain Acid Wash

    Well I decided to go ahead and try the No Drain Acid Wash as described by TXFlyGuy.

    Yesterday's test results.
    FC 1 Been letting it get low in preparation.
    CC 1 Starting to see algae.
    pH 7.5 Been holding it between 7 and 7.5 to try and slowly dissolve the scale.
    TA 40
    CYA 20
    CH 250 See note below.
    Borate 5
    Temp about 65
    CSI calc -0.72

    An aside regarding the CH value. For those of you (duraleigh in particular) who were advising me on my previous thread "Trouble Identifying Stains" I previously thought my CH was much higher. In part it has come down due to rain dilution but mostly I think it was operator error on the testing. The color change is subtle for my particular type of color blindness and I was getting some of the unusual color changes too. Getting my wife to look at the color change, and adding two drops of the third reagent before the second has given me two consistent tests less than 300 now.


    Started no drain acid wash at 1am on 2/24/12.
    Added 1 gallon of Leslie's "Stain and Scale 2" in lieu of the Scaletec recommended in the no drain acid wash thread. I could not find the Scaletec locally (till this morning).
    Raised water level to cover most of the tiles and my usual water-line.
    Added a quart of acid to get to about 7ph overnight.
    Circulated for an hour.

    In the morning there was no obvious improvement (maybe a little at the water line) so I went to the pool store and bought 8 gallons of acid, polyquat and found some Beautec as recommended in the no drain thread.
    Added the polyquat and Beautec (64 oz) and circulated for a couple of hours. Stopped the pump and removed the timer block so it won't turn on again until I raise the pH (maybe in a couple of days).
    Tried out the stainless steel brush, wow it is much harder to push around than the nylon(?) one.
    pH measured 7.2

    Added 8 gallons of acid, expected pH will be 4.4 from pool calc don't know how accurate that is, could not find strips that go that low and didn't look real hard.
    Brushed the entire pool.
    As expected the pH is <6.8. I was surprised by how the color is not so different (to my partially color blind eyes) from 6.8 if at all. I understand the advice not to let the pH fall to 6.8 cause you really don't know how low it is beyond that.
    26600 Gallon | In Ground Plaster
    Sand Filter Hayward S310S 500 Lbs Sand 4.9 sqft | Pump Hayward RS1500 (1.5HP motor)

  2. #2
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    Re: Just started No Drain Acid Wash

    And a few pics.
    In this one you can just make out the stains between the darker tree reflections. The water is kind of cloudy from the brushing and lawnmowing activities this morning. The stains are the same ones shown in my previous "Trouble Identifying Stains" thread.


    Here are the steps. The black spots are from the lawn mowing debris.



    And overall cloudiness.
    26600 Gallon | In Ground Plaster
    Sand Filter Hayward S310S 500 Lbs Sand 4.9 sqft | Pump Hayward RS1500 (1.5HP motor)

  3. #3
    Mod Squad Melt In The Sun's Avatar
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    Re: Just started No Drain Acid Wash

    Maybe my memory is on the fritz, but I dont think there's any reason to lower your FC unless you're doing the ascorbic acid treatment. Are you planning on doing that, or just trying to remove scale?
    11,200 gal, Pebble-Tec; Tristar 2-speed 1hp - Swimclear 325 ft2 cart - SWG - A & A in-floor cleaner - Heat pump. For the poolside cooking, a Yoder Wichita and a Big Steel Keg!
    TF Test Kits -- PoolMath -- Pool School
    Make each day your masterpiece. - John Wooden

  4. #4
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    Re: Just started No Drain Acid Wash

    I'm not really sure if the FC needs to be lowered or not. In this thread http://www.troublefreepool.com/resid...le-t38546.html TXFlyGuy noted that "The total alkalinity was brought down to zero, as was the chlorine, and the PH was around 4 or so, perhaps less." So I may have mixed up an incidental occurrence with the ascorbic acid treatment regime.

    Will normal amounts of FC get knocked down to zero by this much acid? I've got the polyquat in there so I'm not worried about algae showing up for now.
    26600 Gallon | In Ground Plaster
    Sand Filter Hayward S310S 500 Lbs Sand 4.9 sqft | Pump Hayward RS1500 (1.5HP motor)

  5. #5
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    Re: Just started No Drain Acid Wash

    Ok, it's been a little more than 2 days since adding the acid. I brushed every 1.5-2 hrs the first day, only a couple of times the second due to prior commitments. Back on schedule today. The scale on the pool bottom and sides appears to be going away but there is still a long way to go. The pool steps don't really look much better though. I guess I'll go through tomorrow and see what happens.

    For those who are concerned about the effect of the low pH on the plaster, what should I be looking for? Each time I brush, I stir up some dust, but I'm not sure if that is scale coming off, plaster, or or just settled dust.
    26600 Gallon | In Ground Plaster
    Sand Filter Hayward S310S 500 Lbs Sand 4.9 sqft | Pump Hayward RS1500 (1.5HP motor)

  6. #6
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    Re: Just started No Drain Acid Wash

    I think I'm going to cut off the acid wash tomorrow. Can't brush much with work, and I'm not sure what effect it is having now.

    I plan to raise the pH using Borax. I want to add borates anyway, the acid is in there so why not now? My plan is to add about half the borax brush and check ph. Add half of what's left and check again to avoid over shooting to the high side. By my calcs I will need to add some baking soda anyway to finish bringing the pH up.

    Anyone see a problem with that plan? Will it make any subsequent stain / scale treatments harder to accomplish? The steps still don't look so good.

    Thanks.
    26600 Gallon | In Ground Plaster
    Sand Filter Hayward S310S 500 Lbs Sand 4.9 sqft | Pump Hayward RS1500 (1.5HP motor)

  7. #7
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    Re: Just started No Drain Acid Wash

    By my calcs I will need to add some baking soda
    Bill, did you mean borax? Baking soda has little affect on pH, it is used to adjust TA.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
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  8. #8
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    Re: Just started No Drain Acid Wash

    Well, I did mean baking soda to touch the pH up after adding my borax. On one of the previous no drain acid wash threads there was some discussion where chemgeek said what I understand to be that with a lot of acid in the pool, baking soda would bring the pH up due to CO2 release.

    That said, since I am trying to do most of the work with borax, the baking soda may not work the same way with the pH close to target. I suppose I'll buy some washing soda (pH up) after work and use that. Then use baking soda to bring the TA back into line if I need to. Thanks for the input.
    26600 Gallon | In Ground Plaster
    Sand Filter Hayward S310S 500 Lbs Sand 4.9 sqft | Pump Hayward RS1500 (1.5HP motor)

  9. #9
    Mod Squad Melt In The Sun's Avatar
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    Re: Just started No Drain Acid Wash

    Well, please let us know how it turned out, once you can see the whole thing again (and once you swim again in a month or two).
    11,200 gal, Pebble-Tec; Tristar 2-speed 1hp - Swimclear 325 ft2 cart - SWG - A & A in-floor cleaner - Heat pump. For the poolside cooking, a Yoder Wichita and a Big Steel Keg!
    TF Test Kits -- PoolMath -- Pool School
    Make each day your masterpiece. - John Wooden

  10. #10
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    Re: Just started No Drain Acid Wash

    OK, I ended the treatment last night. First I pumped out the excess water I had previously added to get it above the white stains on the tile. Then left it on circulate (I had not been circulating at all during the treatment). Added 16 (72oz) boxes of Borax in 3 steps, measuring pH between each addition, which was still below 6.8 after all was added. I then used the pool calculator to see how much pH up to add, assuming I was at 6.8 and going for 7.5. I managed to overshoot to about 8. Maybe I had not given the borax enough time to fully dissolve and that caused the overshoot. It took about a gallon of acid to bring it back to a stable 7.5 which held overnight. The TA was 40 after all this. I was expecting to have to add baking soda to restore this but it is the same now as before. I can see the effects of the Borates on pH buffering. I have to add a lot more acid to bring the pH down now. I think that is good because I had to add acid quite often before to keep the pH down.

    I restarted the polaris to keep the dust stirred up and am filtering.
    I also decided to go for mustard shock chlorine levels, on the theory that some of these stubborn stains may be organic and I have not had Chlorine in the pool for 4 days.

    Overall, at the moment, I am not so excited by the results versus the effort. I can still see evidence of the stains on the walls, floor, and steps. I'll get some "after" pictures in a day or two after the water clears up and I don't have a layer of dust on the stains. It certainly seems much smoother when brushing the floor so maybe what is needed is a second treatment. I considered adding additional acid half way through on the theory that if I was using "just enough" to begin with maybe some was used up very quickly with the top layers of scale raising the pH above the effective level. It is frustrating to get so used to testing and knowing exactly what the water is doing and then flying blind down in the low pH end of things.

    The treatment did take care of the white scale on the top of the tiles above the normal water line. That was not bothering me but it does look great. If that was my main concern I think I would try getting in the water and applying acid directly.

    We will see how much the other stains were improved. I'll also look for evidence of plaster damage due to the treatment, though I am still unsure of what to look for there. Seems to my "pool newbie" mind that such treatments may reduce the plaster thickness, but unless there were cracks to widen or some such what damage is possible? What is the typical thickness of the plaster finish?
    26600 Gallon | In Ground Plaster
    Sand Filter Hayward S310S 500 Lbs Sand 4.9 sqft | Pump Hayward RS1500 (1.5HP motor)

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