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Thread: Reducing CYA, the Tarp method

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    Reducing CYA, the Tarp method

    Hi guys,

    Recently I found out that my CYA level was way too high, somewhere between 250 and 300.

    Having to replace around 80% of the water, doing it in one go would be too dangerous for my old vinyl liner, and multiple drain and refills would waste a lot of water.
    Searching on the forum for people in my situation, I found that the tarp method would be the best alternative. I recently purchased a black solar cover (thick bubble wrap) which is too big for my pool, so it was perfect for this.

    Here is my pool before the process (I will need to SLAM it after the CYA is back to standard levels),
    https://www.dropbox.com/s/doc1cmibz6...5051.jpg?raw=1

    I don't have a main drain, and my vacuum cap doesn't make a good seal, so I used this pump to drain the water in the skimmer, and then set the valve on my filter to waste. It is not ideal as a lot of air was sucked in the main pump through the skimmer, but in the end the pool drained successfully.
    https://www.dropbox.com/s/rh68nwg1cx...5442.jpg?raw=1

    Here is the new water filling the sheet, at first I was afraid that the bubble sheet would want to float up, but it worked very well. I think it even added a little stability, keeping the sides of the sheet out of the water even when not properly maintained.
    https://www.dropbox.com/s/bvwmt5px06...0046.jpg?raw=1
    https://www.dropbox.com/s/uzznjv7jug...2407.jpg?raw=1
    https://www.dropbox.com/s/55b7w9e8p8...2526.jpg?raw=1

    here is the pool a little later, I used duct tape to maintain the two sides at the same height, but there is really no tension in them,
    https://www.dropbox.com/s/ia5e2fhgn2...1815.jpg?raw=1

    And here it is at the end of day two, the tarp is full and touching the bottom, there is still a bit of old water on the sides but the tarp is too small to go much lower.
    https://www.dropbox.com/s/wbua6542hw...2614.jpg?raw=1

    And then, the "grand final", the removing of the sheet :
    https://www.dropbox.com/s/isa0bzgolf...oval.mp4?raw=1

    Anyway this worked very well and my CYA is now even lower than I excpected, less than 30! Oh well, it's easier to raise than to lower
    I'm ready to begin the SLAM!
    7.25k gallons IGP, vinyl, sand filter, solar heater (manually operated)

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    Re: Reducing CYA, the Tarp method

    Thanks for sharing a play by play. We have had several people do something similar with success. SLAMs Away!

    By the way, looks like you have a great helper managing the water input (=
    310 gallon Tiger River Sumatran Spa, covered, standalone, fiberglass, Bleach
    11,000 gallon in-ground plaster pool, Hayward SmartFilter 550 (cartridge), CompuPool(Hayward) T-15 SWG, Hayward Super II pump
    Taylor Test Kit K-2006C, K-1766, SampleSizer, SpeedStir, Polaris P825

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    Richard320's Avatar
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    Re: Reducing CYA, the Tarp method

    Thanks for posting this! It's been a long time since anyone tried this method. Glad it worked.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Reducing CYA, the Tarp method

    Yes I have seen only a few posts showing this method, so I thought it would be interesting to take pictures. It is really easy to do once you have a large enough sheet.

    By the way, looks like you have a great helper managing the water input (=
    He is always there to help me tend to the pool, he can't wait to take his first swim!
    7.25k gallons IGP, vinyl, sand filter, solar heater (manually operated)

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    Re: Reducing CYA, the Tarp method

    This method interests me as I also have a vinyl-lined older pool without main drain.

    Am I understanding correctly, that you drain the water below the tarp while you fill new water on the tarp? And this maintains pressure on the vinyl liner so that it doesn't pop out, even with a nearly full drain?
    ~22,000 gal, IG, vinyl lined, ~50 years old
    Hayward high rate sand filter, Zodiac FloPro .75HP, Pentair Intellichor SWG

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    n240sxguy's Avatar
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    Re: Reducing CYA, the Tarp method

    Quote Originally Posted by Harbinger of Fun View Post
    This method interests me as I also have a vinyl-lined older pool without main drain.

    Am I understanding correctly, that you drain the water below the tarp while you fill new water on the tarp? And this maintains pressure on the vinyl liner so that it doesn't pop out, even with a nearly full drain?
    That is correct. The tarp separates the old and new water while still maintaining a safe water level in the pool.


    30K gallon IG vinyl. 1.5HP 2-speed Waterway Mustang pump. 600 lb sand filter. Polaris 280. Circupool SI-60+. TF-100

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    Re: Reducing CYA, the Tarp method

    What size is the pool?

    What size was the tarp?

    That's Nice Work!!
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Reducing CYA, the Tarp method

    That's brilliant! Great job.
    19,000 gal - Vinyl IG - Sand filter -1.5hp. - Taylor k 2006 - Loop Loc cover

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    Re: Reducing CYA, the Tarp method

    Moderators:

    This Post deserves a place in PoolSchool!
    Simple and Brilliant!

    Felipe
    7,500 gal Rectangular, Easytouch 8, Air+water temp sensors, Screenlogic2, IC40, intellibright5g color12v, Intelli pH, SD 70 filter w/Zeolit, Magicstream Laminars, waterfall. Raised Monolithic concrete lined with glass beads.

    In Sunny Monterrey,Mx!

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    Re: Reducing CYA, the Tarp method

    I wish I saw this last year when I was doing partial drains and refills.
    20K gallon 32 ft x 16 ft vinyl liner in ground pool || sta-rite modular media P150 cartridge filter || .75 HP whisperflo dual speed pump
    Taylor K-2006 Test Kit. || Dohney's Discovery Robot

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    Re: Reducing CYA, the Tarp method

    Quote Originally Posted by bigevilgrape View Post
    I wish I saw this last year when I was doing partial drains and refills.
    Can you imagine the size tarp you would have needed? Would have been epic!
    Bob - INTEX 12x24 owner (not setup yet), 'New to me' Kreepy Krauly Sand Shark, Test kit: TF-100 w/Speed Stir

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    Re: Reducing CYA, the Tarp method

    Thanks Everybody, I'm glad I could help the community after all I'v learned here!

    Quote Originally Posted by duraleigh View Post
    What size is the pool?

    What size was the tarp?

    That's Nice Work!!
    The pool is 12' x 22' (if my conversions from meters are correct ) and the tarp is 8x5m (around 26' x 16' 1/2),
    it was clearly not big enough to hold the full volume of the pool, but since you can always lower the level down a little, it was actually sufficient.

    I stopped the filling once the tarp was full (water almost overflowing on both sides) and then only drained until the level was as low as I was comfortable with.
    7.25k gallons IGP, vinyl, sand filter, solar heater (manually operated)

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    Re: Reducing CYA, the Tarp method

    Hi guys,

    I'm back with some news of my pool, and some questions...

    So I had to delay the beginning of my slam due to the installation of my solar heater. It is still in progress but now I can run my pump if I use the bypass.

    Here is the full log of my levels since the beginning 6 days ago :
    http://www.dropbox.com/s/ayqjp29fmd60f0u/Log.PNG?raw=1

    The CYA level was initially low, and as I had a big bucket of trichlor, I wanted to use that as my CYA source. The problem is, Trichlor also contains a lot of chlorine, more than I thought.

    You can see that I didn't add any chlorine after the first 10 ppm to get up to Slam level, but it climbed all the way to 22ppm quickly. I removed the cover (which doesn't let the sunlight through) during the sunny days to deplete the chlorine quicker, and managed to keep the chlorine at "reasonable" levels.

    You can also see that I passed 2 OCLT in a row (My CC are 0 since I added the chlorine), so it should mean that nothing is growing in my pool , now I'm leaving the chlorine get back to standard levels.

    The only concern I have is about my vinyl Liner, it is quite old and there are brown/green stains on the walls, especially on the less exposed side. Could it still be algae at the chlorine levels that I run? I also noticed that the stains are present only under the old water line from when I was working on my heater (water stayed at that level for about a month).

    This picture shows the stains on the bottom, then you can see the old water line where the stain stops, then the actual water line.
    http://www.dropbox.com/s/06rcsg38m1f...2820.jpg?raw=1

    Any Idea on what the stain could be?
    7.25k gallons IGP, vinyl, sand filter, solar heater (manually operated)

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    Razorhog's Avatar
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    Re: Reducing CYA, the Tarp method

    Possibly metal stains, are you filling from a well? I get iron stains filling from my municipal water supply that look very similar.
    SLAM * Chlorine/CYA Chart * Pool Math * Pool School
    17.5k gal IG Fiberglass, Triton II TR60 Sand Filter, Jacuzzi Magum Force Pump 1.5 hp, 3/4 hp booster, Polaris 280, TF-100 Test Kit with Speed Stir

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    Re: Reducing CYA, the Tarp method

    No it's City water, the pool store tested the water before the refill and it was at zero for both Copper and Iron, I could go and check again to see what are my levels now that I drained and refilled.
    7.25k gallons IGP, vinyl, sand filter, solar heater (manually operated)

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