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Thread: Use trichlor pucks to increase CYA?

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    Use trichlor pucks to increase CYA?

    Lots of rain and backwashing this summer has caused my CYA to drop from 50 to a number that I can't read on my Taylor kit (less than 30). So, I've been floating a few trichlor pucks in the floating dispenser thingy. My pH tends to climb, so I'm not worried about that aspect (currently 7.6). My total alkalinity is good at 70, but I wouldn't want it to drop too much. I'm seeing a very slight increase in CYA, so I might abandon this ... but thought I'd get your input. Any problems with this idea, other than it's slow?
    -----------------------------------
    26000 gal, in-ground, vinyl pool
    Hayward S200 sand filter, 1 skimmer, 2 returns
    BBB since the first month! :-)

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    Mod Squad Bama Rambler's Avatar
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    Re: Use trichlor pucks to increase CYA?

    Well Teach, looks like you've been doing a little learning.

    You've covered all the drawbacks, so other than they're slow at adding CYA, as you stated, there's no reason you can't continue. You're obviously keeping a check on your chems. I don't know how much longer your season is, but it might be advantageous to stay the course and add CYA next season if you need it.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    stev32k's Avatar
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    Re: Use trichlor pucks to increase CYA?

    So far this year we have had over 60 inches of rain and I have had to add about 7 lbs of CYA to keep the concentration around 30 ppm. There have been weeks when I had to pump water out the pool several days in a row to keep it from overflowing - the overflow could not keep up.
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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    Re: Use trichlor pucks to increase CYA?

    At the bottom of the Pool Calculator is a function that tells you how much CYA a given weight of Pucks will add to your pool.

    For example, in my pool, 1 puck adds about 1 ppm CYA so when I decided that the CYA was a bit too low at 32-ish, I added 12 pucks over several weeks to the in-line chlorinator and bumped it back up to 50-ish.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

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    Cherie's Avatar
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    Re: Use trichlor pucks to increase CYA?

    I took advantage of a 15 CYA reading (using Dave's BIG CYA tube) this year by using the pucks until it got back up to about 45 (I am trying to keep it at about 25 though). I thought it would take longer, but it only took two months of using 2-3 of the 3" pucks every 10 days or so. It sure was nice to just go out and check the water each evening and once a week, toss the Aquabot in for a cleaning. I keep our TA at 60 and the pH (which I keep at 7.3 - 7.4) seldom needs to be adjusted, except that we've just had 8 days of rain! So I'm thinkin' that from now on, I'll just play lazy when the CYA drops too low and grab the pucks.
    32x16 buried Doughboy, 4' shallow - 7' deep
    Pentair Dynamo 1 hp, 2-speed - Pentair 150# SD40 w/zeolite (75#)
    One skimmer/two returns/Aquabot Turbo T2

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    Re: Use trichlor pucks to increase CYA?

    Quote Originally Posted by Cherie
    I took advantage of a 15 CYA reading (using Dave's BIG CYA tube) this year by using the pucks until it got back up to about 45 (I am trying to keep it at about 25 though). I thought it would take longer, but it only took two months of using 2-3 of the 3" pucks every 10 days or so.
    An increase of CYA from Trichlor of 30 ppm in 60 days is an average daily chlorine usage of around 0.8 ppm per day which is low. That probably means you had some dilution of the CYA from rain during that time. For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm. So even with a low 1 ppm FC per day chlorine usage, Trichlor will increase the CYA by over 100 ppm in 6 months if there were no water dilution. In other words, it doesn't take long for CYA to increase when using stabilized chlorine unless you have a lot of water dilution from regular backwashing, splash-out, or rains, especially in a smaller pool.
    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
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Cherie's Avatar
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    Re: Use trichlor pucks to increase CYA?

    That's odd, Richard. Because during the two months that we used them, we were building our deck. And believe me, we had no rain (or cool breezes!) and we didn't swim all that time, nor did the kids. But from prior conversations with Dave, it seems our pool water simply doesn't use much FC, because even when I use bleach, I rarely have to use more than 1 qt of 6%, even in the hottest weather. I don't recall which thread that conversation came up on.

    So I'm counting our blessings that, not only has this site taught me how to easily and inexpensively maintain our pool, but we seem to need even less than the average user of bleach. I know our pool volume is correct, because one of the nice folks on here helped figure it out! So we'll just keep counting our blessings. And I WILL watch the CYA a little closer the next time I use the pucks. I really prefer keeping the CYA lower, since our pool did very well and we didn't have to use more bleach because of the lower CYA.
    32x16 buried Doughboy, 4' shallow - 7' deep
    Pentair Dynamo 1 hp, 2-speed - Pentair 150# SD40 w/zeolite (75#)
    One skimmer/two returns/Aquabot Turbo T2

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