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Thread: Scale buildup in the plumbing

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    Scale buildup in the plumbing

    Hi guys, I'm looking for some advice on what steps to take next to rid my hot tub of white flakes and finally get clear water. Clear water seems like a pipe dream right now! I flushed the tub and superchlorinated(wasn't sure if it was mold at first) a few weeks ago and I believe that helped, but the flakes are still coming out of the circulation drain everyday. It's beginning to feel like the movie Groundhog day! I wake up, net a bunch of flakes off the bottom of the tub, and then prepare myself to do the same thing the next day. Water is semi cloudy from what I believe to be the breaking down of these bigger flakes.

    400 gallon hot springs tub. The PH was over 8.0 for quite a while(maybe a year +, I'm not exactly sure) until I started taking care of it. Hose water is ~8.4 and 150 TA and I know not much Spa down was used by previous caretaker.

    PH 7.4
    TA 35
    CH 140
    CYA ~20
    CSI -.64
    temp 101

    Are these numbers fine in your opinion? I can see white deposits inside the clear plumbing when I take the front panel off. Should I drop the PH any further? My TA is very low and might be down around 25 if I try to add acid. I believe dichlor additions alone may get me to 7.0 in a week or less because it seems to be having quite the negative effect on PH at my current TA level, even after aeration is factored in. PH was 7.6 2 days ago.

    I also have another bottle of enzyme that I could run through the system. Winter is fast approaching and I'm trying to get it in check before it's too late. From what I've read, this might not be a quick fix at all and maybe the best thing to do is let the low PH do its thing. Would love to hear from the experts. Thanks!
    Hot Spring Vanguard

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    Mod Squad Patrick_B's Avatar
    Join Date
    Jun 2011

    Re: Scale buildup in the plumbing

    Welcome to the forum! Sorry your question hasn't been answered, and spas are my weak point. We have a few around who are much better answering these than I. I will say it just may take a while to rid the system of all the scale.
    TFP Moderator
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    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Scale buildup in the plumbing

    The Dichlor is net acidic so will continue to lower your TA so you'll need to bring it back up, but don't need it above 50 ppm. If you are going to be using Dichlor-then-bleach, then you'll need to use 50 ppm Borates for additional pH buffering against a rise in pH since you'll be keeping your TA low at around 50 ppm in that case.

    As for the scale, having the low TA, CH and pH (i.e. a negative saturation index) will help to dissolve it, but you don't want the pH to get too low for too long since you don't want metal corrosion in your heater. For sure don't let the pH get below 7.0 for any extended period of time. Better than lowering the pH, you might consider using a scale removal product. We don't get enough of these reports to know which product to recommend. Most stain & scale removers are a combination of an acid, a reducing agent, and a metal sequestrant (including binding to calcium).
    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
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  4. Back To Top    #4

    Join Date
    May 2011
    Abilene, KS

    Re: Scale buildup in the plumbing

    Talk to a Hot Springs dealer. I went through this with a Hot Springs that I got from a family member. They had REALLY hard water and rarely checked ph so there was alot of calcium built up in the plumbing. The dealer had me lower the ph (I can't remember to what or for how long). This cleaned everything out and I never had another problem (I paid attention to water balance).
    25,000 gallon Vinyl Lined Inground. One skimmer, 2 returns. Pentair WhisperFlo WFDS-4, Hayward Pro Grid DE 3620 with VariFlow valve, LaarsLite 2 propane heater

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    linen's Avatar
    Join Date
    Jul 2010
    Twin Cities, MN

    Re: Scale buildup in the plumbing

    Welcome to tfp, IM_ALL_IN

    Chem geek gave you great advice. As he said, keep ph on the lower end but not below 7 and keep TA at 50 ppm and I would echo the use of 50 ppm borates.
    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.

  6. Back To Top    #6

    Re: Scale buildup in the plumbing

    Appreciate the tips and advice guys. I flushed the system with jet clean and then refilled and kept the PH in the 7-7.4 range for the past month. I've also been adding stain and scale preventer every week or so. It's looking tons better, still a small amount of flakes coming out of the circulation pipe everyday, but nowhere near what it was. The tub was really in need of some TLC. I also want to add that vacuuming out the plumbing was HUGELY beneficial for me. I blew the jets out first of all and then focused deep within the system. There's a reserve area(I think for the waterfall) and the water must of sat stagnant for a long time b/c there was tons of build up was in there. First I vacuumed out all the water and then I continually shot water down there and vacuumed it back out. This really got a bunch of crud.

    I will look into the borates if need be, but the PH has been holding steady with the TA ~40. I'm keeping a good eye on it. One more flush and the tub should be perfect, unfortunately the weather doesn't want to cooperate so it might be a while
    Hot Spring Vanguard

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