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Thread: No Drain Acid Wash

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    wmwinn's Avatar
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    No Drain Acid Wash

    For the last few seasons, I've seen more and more evidence of pool bottom and wall scaling. The pool is 10 years old (24K gallon), and the water comes from a well (which is hard to begin with). It's getting so bad, that swimmers come out of the pool with their feet bleeding. Very rough indeed.

    This year, I want to try the No Drain Acid Wash for the next 5-7 days. Here are my current water conditions:

    Temp = 74
    FC = 3
    CC = 0
    pH = 7.5
    TA = 140
    CH = 600 !!
    CYA = 0 (automatic pool cover, very little sunlight exposure)

    I plan to take the pH down to 6.0, and brush 4 times a day with nylon and steel brush. I do not have a heater, no metals in the plumbing - so I plan to keep the pump on the entire time. That way, I want to see the cloudiness dissipate and perform necessary backwashing while the process is going on. If I can keep the water fairly clear during this process - the advantage is to know when the scale is gone, and then bring the pH back up using baking soda.

    Is there a way to measure pH below 6.8?

    Am i missing anything? This forum has helped me out many times in the past, and I'm getting a lot of education from other pool owners at TFP.

    thanks,
    - Mark -
    Inground gunite 34x28 sport pool (24,300 gal)
    Hayward T-Cell-15 SWG, Solar heating
    Hayward sand filter, automatic cover
    Muriatic acid injection using fish tank peristaltic pump

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    Mod Squad jblizzle's Avatar
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    Re: No Drain Acid Wash

    You can not measure the pH that low directly, but by using the base demand test, I think that would give you an idea of what your pH is. This demand test is not part of the TF-100, but is part of the K-2006. What kit do you have?
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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    wmwinn's Avatar
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    Re: No Drain Acid Wash

    I have the TF-100, and a K-1004 - which I believe tests the acid demand... but not the base demand.

    Any advice of whether to utilize baking soda vs. soda ash? I realize that soda ash will use fewer lbs, but are there other advantages to soda ash?

    thanks,
    - Mark -
    Inground gunite 34x28 sport pool (24,300 gal)
    Hayward T-Cell-15 SWG, Solar heating
    Hayward sand filter, automatic cover
    Muriatic acid injection using fish tank peristaltic pump

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    Mod Squad jblizzle's Avatar
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    Re: No Drain Acid Wash

    baking soda and soda ash are used to adjust different things ... TA vs. pH:
    Recommended Pool Chemicals
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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    wmwinn's Avatar
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    Re: No Drain Acid Wash

    Update: I started the process tonight by adding 3 gallons of MA. This dropped my TA from 140 to 70. Brushed all surfaces. Wish I knew what the pH level was!

    Inground gunite 34x28 sport pool (24,300 gal)
    Hayward T-Cell-15 SWG, Solar heating
    Hayward sand filter, automatic cover
    Muriatic acid injection using fish tank peristaltic pump

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    wmwinn's Avatar
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    Re: No Drain Acid Wash

    I added another gallon of MA today, knocked the TA down to 50. First 24 hours showed some minimal improvement with scale. I'm going to be very patient and let it work for another 3 days. Pump has been of the entire time. Brushed 4 times today.

    Inground gunite 34x28 sport pool (24,300 gal)
    Hayward T-Cell-15 SWG, Solar heating
    Hayward sand filter, automatic cover
    Muriatic acid injection using fish tank peristaltic pump

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    wmwinn's Avatar
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    Re: No Drain Acid Wash

    Added another gallon of MA (total of 5 gal so far), TA has reduced further to 30. Scale remains on bottom of pool. I've been using a nylon brush, but will start using a stainless steel brush next. Each day, the CH has increased. Day 1: 600, Day 2: 630, Day 3: 725. I hope that means the calcium scale is going back into solution.

    With a super-low pH during the acid wash - Can I trust the CH test results?
    Inground gunite 34x28 sport pool (24,300 gal)
    Hayward T-Cell-15 SWG, Solar heating
    Hayward sand filter, automatic cover
    Muriatic acid injection using fish tank peristaltic pump

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    wmwinn's Avatar
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    Re: No Drain Acid Wash

    Quote Originally Posted by jblizzle View Post
    You can not measure the pH that low directly, but by using the base demand test, I think that would give you an idea of what your pH is. This demand test is not part of the TF-100, but is part of the K-2006. What kit do you have?
    I'm interested in hearing how the base demand test can provide me with an estimate of pH. After the normal pH test, I add Taylor reagent R-0006 to the sample, and count how many drops until a target pH color is seen. How will #drops get converted to a current pH? Is there a table somewhere that converts #drops to pH?

    thanks,
    - Mark -
    Inground gunite 34x28 sport pool (24,300 gal)
    Hayward T-Cell-15 SWG, Solar heating
    Hayward sand filter, automatic cover
    Muriatic acid injection using fish tank peristaltic pump

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    Mod Squad jblizzle's Avatar
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    Re: No Drain Acid Wash

    Well there is a table with the kit that tells you how much soda ash (or something) would be required. You could then try to user PoolMath to back out the pH. But in hindsight not sure how accurate this would be since the demand test makes an assumption about your TA which may not match what you have.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    Re: No Drain Acid Wash

    Instead of brushing, why not try using pressure cleaner to fasten the process?
    33k gal IG concrete pool with ceramic tiles. Outdoor with transparent roofing.
    2.2 HP Davey pump (PowerMaster PM450), 5.4 sq ft Davey sand filter (Crystal Clear FG32)
    Backup filter & pump for vaccuming

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    Mod Squad jblizzle's Avatar
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    Re: No Drain Acid Wash

    Quote Originally Posted by yoitsme View Post
    Instead of brushing, why not try using pressure cleaner to fasten the process?
    Because the pool is not drained and that could also damage the plaster.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    wmwinn's Avatar
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    Re: No Drain Acid Wash

    Don't want that.
    Inground gunite 34x28 sport pool (24,300 gal)
    Hayward T-Cell-15 SWG, Solar heating
    Hayward sand filter, automatic cover
    Muriatic acid injection using fish tank peristaltic pump

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    wmwinn's Avatar
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    Re: No Drain Acid Wash

    After 3 Days of the "No Drain Acid Wash" experiment, here are my findings:

    Day 0 - FC: 3, pH: 7.5, TA: 140, CH: 600, Temp:74
    Added 3 gallons MA, pump OFF, cover open, brushed 4 times with nylon brush

    Day 1 - FC: 1, pH: << 6.8, TA: 70, CH: 630, Temp: 68
    Added 3 lbs granular CYA, 12 oz algaecide, 1 gallon MA, brushed 3 times with nylon brush

    Day 2 - FC: 0, pH: << 6.8, TA: 40, CH: 725, Temp: 66
    Added 1 gallon MA, brushed 3 times with nylon brush

    Day 3 - FC: 0, pH << 6.8, TA: 30, CH: 750, Temp: 68, base demand test: 5 drops
    Added 1 jug of bleach, 1 gallon MA, brushed 2 times with steel brush

    Without knowing the pH level, I'm having trouble figuring out how acidic the water is. The scaling along the walls and floors of my white plaster pool have not shown much improvement. I have some optimism around the CH increasing with each day - I would expect that as the water absorbs more calcium with such a negative CSI.

    The idea to measure the base demand test was interesting. It only took 5 drops to bring the pH color back to a 7.5 reading. I don't have access to the Taylor base demand table - but found one on the internet that shows only 2.5 lbs Soda Ash for 20K pool for a 4 drop base demand test. That doesn't seem like much to me.

    Perhaps my pH is not low enough?

    Anybody have ideas what to do next? I have maybe 2 more days with this experiment before the family revolts and will want to swim. Anybody with "No drain acid wash" experience out there?

    thanks,
    - Mark -
    Inground gunite 34x28 sport pool (24,300 gal)
    Hayward T-Cell-15 SWG, Solar heating
    Hayward sand filter, automatic cover
    Muriatic acid injection using fish tank peristaltic pump

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    No Drain Acid Wash

    5-15-2014
    Take a sample of your water to a local lab, not a pool store, and get a pH reading. I use Western Analytical <http://www.wal.cc/> in Chino, CA.

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    Re: No Drain Acid Wash

    Thanks for all the help and ideas during this experiment. Here are my conclusions and thoughts:

    My 10 yr old pool was in dire need of an acid wash. Rough "sandpaper-like" scaling on bottom and walls of the pool. I did NOT want to dump the water for a professional acid wash - we live in a desert! There was a 4-5 day span of cold weather this spring, where my family knew that swimming was out of the question. Perfect timing to try this experiment.

    My target pH during this "no drain acid wash" was 6.0. I believe I hit that number and kept it there for 4 straight days. Each consecutive day, there was an increase in the CH number, proof that some calcium was going back into solution.

    I expected "clouds of dust" making it difficult to see the bottom when the acid started softening the scale. That did not happen. Water stayed nice and clear the entire time. After LOTS of brushing, I learned that steel bristles make easier work than the nylon brush variety. Very minimal "clouding" during each brush stroke along the white plaster.

    I was worried about the stainless steel trim rings around my pool lights. Didn't want them to corrode and lose their finish. They stayed shiny and good looking during this project.

    Overall conclusion:
    I could have added more acid from the very beginning (try to get pH to below 5) and the results may have been better. Perhaps I was too "risk adverse" my first time trying this. There was some removal of my scale, which is good - just not totally removed. With such an acidic pool after the experiment, I decided to add Borates this year, and brought the pH back up using only Borax (608 oz of 20 Mule Team). Before the "no drain acid wash" my TA was 140, and afterwards it's sitting at 70 - much better for a SWG pool.
    Inground gunite 34x28 sport pool (24,300 gal)
    Hayward T-Cell-15 SWG, Solar heating
    Hayward sand filter, automatic cover
    Muriatic acid injection using fish tank peristaltic pump

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    Re: No Drain Acid Wash

    I have tried the No Drain Acid Wash successfully. The PH was way below 6 and TA was 0. Only then it works. It has to become a acid pool. I pumped 16 gallons acid in 26,000 gal pool.

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    wmwinn's Avatar
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    Re: No Drain Acid Wash

    Thanks for the info, poolbee!

    Inground gunite 34x28 sport pool (24,300 gal)
    Hayward T-Cell-15 SWG, Solar heating
    Hayward sand filter, automatic cover
    Muriatic acid injection using fish tank peristaltic pump

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