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Thread: CYA and summertime trends

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    TulsaKevin's Avatar
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    CYA and summertime trends

    Since I have a SWG and don't need any chlorine......, jk, I like to get some of the administrators BP up with comments like that.

    Lets start again, I have a SWG cell rated at 40k, my pool is 55k, and was built in the winter. I have used the TFP from the get go (glad I did, as soon as the month was over when the "had control" of the water, I used my handy dandy TF-100 and the chemistry levels were deplorable. One more tangent, I did recently purchase a PH meter because I never like the guess that color game, really like it so far, I continue to use the qualitative test as well, just to hone my skills, but it makes me feel better about knowing more accurately the ph, very similar from the FAS-DPD Chlorine test vs the sticks, or color chart.) I have brought the CYA up from 20 to 60. I am going to take it to 70 this week. I like to use the liquid CYA and wait a week before adding more ( I do use the Trouble free calc, however, I want to avoid too much CYA for all of the bad reasons that yall know).

    Question #1. Those who have gone a few summers, what changes in CYA did you see from beginning to the end of the season. I know that CYA does not get used (how in the world have people used pucks for so long is crazy to me), seems like it will always increase the CYA to unacceptable levels in every single pool, due to chlorine consumption and the CYA just hanging out and adding up. This leads me to believe that there is a certain amount of CYA loss per season, due to splash out and rain dilution, though evaporation and autofill should not effect it. How much do yall typically have as a loss of CYA. If you start at 70 in a swg, and don't add any, what is the average drop rate ( I know there are variables, ie but on average).

    Question #2. What length of time do yall have your filter running. My filter (sand with variable speed) runs enough already at 12 hours to keep 95 percent of the debris, I can see that the screws are Phillips head that hold the main drain cover in at 10 feet. With the SWG cell at 90%, it maintains around FC of 2, I augment with liquid chlorine. I have just recently increased it to 18 hours run time just so I can have more time with the SWG cell running. My question, on average, what is the typical run time for the filter ( I have read many articles on this, but again, not for filtration, but just for SWG production) If most people are running the filter at 12 or less, I could run my for about 8 (at least in the winter and still do fine on filtration). I am trying to decide if I want to go ahead and add a second SWG cell, the PB and I discussed that at the very beginning, but wanted to wait to see how well the one would work first. Pros and cons of up front cost of the SWG, vs long run cost of running the filter longer, and increasing the wear and tear on the filter pump.

    Thank you for your all of your help, just getting ready for the first summer and want to see what the normal trends are so I can plan ahead.

    Fyi, for new people don't buy anything from Leslies, I found CYA for nearly half the price on amazon, and I use chlorine from walmart and acid from Lowes.


    Getting excited about swimming season, we have set May 1st (18 days and counting) as the date to turn the heater and heat/chill pump on and go for it. We have taking a few dips already with the water temp at 65, it was to say a little brisk.
    55,000 gallon freeform L-shape 40x50ft, 3'8-10', 150' perimeter, gunite, pebbletec (tbd), sand filter, 2hp Ecostar variable speed pump, 400k gas heater, Aquacomfort heat/chill pump, 8 jet spa with 2hp blower, limestone grotto waterfall, 20 ft BYOS slide with arch and water fall, grand effects wall torches and fire bowls, 1m diving platform with 14ft board, gold line salt system, full automation, stamp, stained and salted concrete

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    Mod Squad Bama Rambler's Avatar
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    Re: CYA and summertime trends

    The fact that you're in Tulsa is gonna make your experience different than mine, but I usually lose a little (10 - 15 ppm) CYA during the year from splash out and due to the amount of rain (and therefore overflow) we get here. You may find that you lose about the same amount or you may lose less.

    Since you have a VS pump, You can either run it longer to produce more FC or you could possibly add a second SWCG in parallel to the current one and run the pump less. If electricity is cheap where you are it may make more sense to run the pump at the lowest speed that the SWCG will produce FC at rather than investing in a second SWCG.
    Dave J. TFP Moderator
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    cowboycasey's Avatar
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    Re: CYA and summertime trends

    Hey there, your right up the road from me From your sig it looks like you have a very nice pool going.

    1. Mine dropped from 80 to 70 this year, so with the + or - 10 on the CYA test I would say its close... I am going to watch my fc levels and see if I need to add some CYA this summer.. You are correct in saying it fluctuates, it all depends on splashout and runover/off.

    2. run time for us SWG people is most dependent on how much fc is generated... whether you run it 12 hours a day at 50% or 24 hours a day at 100% your using the same amount of cell life.. From the sounds of it your going to need to run yours 24 hours a day and still may need to dose with liquid. With a CYA of 70 you want to always stay above 3fc and target 5fc, and if you go to 80 its 4fc and target 6. I like to always stay above 5 but that is just what I do

    What would I do, I would probably add another 40k or 60k SWG in the loop and run the lowest they will run with your VS pump.. On the other hand running your VS pump on 1100 rpm (or whatever the lowest the SWG works at) and your SWG at 100% 24 hours a day may get you close, really close... That will use the SWG up faster but cheaper than buying/installing another unit..

    Hope this helps
    Pool: Intex 16x32 15000 gal, 2 speed 340042, Pentair CC320 Filter, CircuPool SJ45 Salt System, Intermatic PE653RC; Hot Tub: 650 Gal SWG Megachlor
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    n240sxguy's Avatar
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    Re: CYA and summertime trends

    My pool is about 32k gallons, and my swg is rated for 60k. I think the longest I had to run it mid summer last year was 8hrs. I started last season at 70ppm cya. I think I added a little bit mid season. I'd say I probably lose 10ppm over a season due to rain and splash out.


    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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    DaninFLA's Avatar
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    Re: CYA and summertime trends

    with that size of pool, i think you are going to need a second cell, or you are going to be running your cell/pump a really long time each day, but at least with the VS pump that will be cheaper.
    Dan
    9,000 gallon in-ground Saltwater pool, plaster, cartridge filer, 1.0 hp pump, Hayward T-15 SWCG, TF-100
    Pool School - Chlorine / CYA Chart; Pool School - Test Kits Compared;

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    Mod Squad pooldv's Avatar
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    Re: CYA and summertime trends

    I would say 3-5 ppm CYA loss per month is an average. During winter you can probably run 2 hours AM and 2 hours PM or less. I run my VS pump at 1100 rpm for filtering and making chlorine, it only uses 150 watts. At 10.25c/kWh I can run my pump 24x7 for 12 bucks a month. And I often do because we have so many trees dropping stuff in our pool spring and fall. My SWG is on its own timer and I set the SWG run time independent of the pump run time. During the main swim season I usually run my pump 12-14 hours (mostly for solar heat) and my SWG about 8 hours.

    I would give higher CYA a try in the middle of summer. CYA at 80 or 90 could reduce your chlorine loss to the sun down to 2 ppm/day.
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    Richard320's Avatar
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    Re: CYA and summertime trends

    It looks like you have the T-15 cell, which is rated at 1.4 lbs output. That's at 100% for 24 hours.

    Effects of adding Chemicals in poolmath says 22.4oz Cl2 gas will add 3.1 FC to a 55,000 gallon pool. That's not an unreasonable daily loss if there's a lot of sun or organic debris and dust or a lot of swimmers. You might have to run the pump and SWG 24/7 to keep up with the demand. Even at a reasonable 2 FC loss per day, that's still running the pump 16 hours a day and the SWG at 100%.

    I see a second SWG plumbed parallel to the first in your future. That would still mean something like 8 hours/day at 100% SWG output.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    TulsaKevin's Avatar
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    Re: CYA and summertime trends

    Always great advice. I will give them a call and see how much the extra cell will run. I don't mind augmenting with liquid chlorine, but it will be nice to not have to if I am gone on vacation, forget or don't remember to buy more bleach.


    Thanks again.
    55,000 gallon freeform L-shape 40x50ft, 3'8-10', 150' perimeter, gunite, pebbletec (tbd), sand filter, 2hp Ecostar variable speed pump, 400k gas heater, Aquacomfort heat/chill pump, 8 jet spa with 2hp blower, limestone grotto waterfall, 20 ft BYOS slide with arch and water fall, grand effects wall torches and fire bowls, 1m diving platform with 14ft board, gold line salt system, full automation, stamp, stained and salted concrete

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