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Thread: I'm assuming there's no chance the CYA dropped like that

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    I'm assuming there's no chance the CYA dropped like that

    I just tested my CYA for the first time since last summer when I brought it down to about 40-50 ppm through draining and refilling. I used the Taylor kit to test and felt like I had good results. When I tested the same way today, it registered essentially 0ppm (solution was totally clear). Could the reagent have gone bad? My kit is no more than 2 years old, I think about a year. I'm assuming there's no chance the CYA dropped like that over the winter with minimal water topping off.
    15K gal, IG plaster, 3/4 HP pump, Pentair CCP320 320 sqft cartridge filter, Letro Legend cleaning robot

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    JasonLion's Avatar
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    Re: I'm assuming there's no chance the CYA dropped like that

    It is very plausible that CYA fell over the winter. That happens often enough. Certain kinds of soil bacteria can consume CYA when FC is zero.

    The CYA reagent can go bad, but it takes a lot longer than 2 years.
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    Re: I'm assuming there's no chance the CYA dropped like that

    OK, thanks. So the recommendation is to try raising to testable levels (20ppm?) and verify the test is working, then go from there to 30-40?
    15K gal, IG plaster, 3/4 HP pump, Pentair CCP320 320 sqft cartridge filter, Letro Legend cleaning robot

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    Richard320's Avatar
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    Re: I'm assuming there's no chance the CYA dropped like that

    Quote Originally Posted by kcbaltz View Post
    OK, thanks. So the recommendation is to try raising to testable levels (20ppm?) and verify the test is working, then go from there to 30-40?
    Sounds reasonable. You might still have something less than 20 in the water right now. It's better to work up than overshoot.
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    Re: I'm assuming there's no chance the CYA dropped like that

    If it's okay for me to add, JasonLion helped me with the same problem. I thought I too had 0 cya. I only added enough to get me to 20 thankfully. The next week I tested at 45. I think my water was too cold to test correctly. Also Jason said the test is subjective + or - 15-20.
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    Mod Squad pooldv's Avatar
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    Re: I'm assuming there's no chance the CYA dropped like that

    Good input, thanks for adding.
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    Re: I'm assuming there's no chance the CYA dropped like that

    I added about 20oz yesterday (15,000 gal pool) and today it's still not measuring above 20 ppm, but the test solution no longer looks clear. I'm going to hold off for a while since I've heard it can take up to a week for the CYA to be dissolved.
    15K gal, IG plaster, 3/4 HP pump, Pentair CCP320 320 sqft cartridge filter, Letro Legend cleaning robot

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    Mod Squad pooldv's Avatar
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    Re: I'm assuming there's no chance the CYA dropped like that

    Yes, that's right, wait a week. Patience is important here.
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    Re: I'm assuming there's no chance the CYA dropped like that

    It seems Cya loss over winter is more common than we used to think. It seems pretty common actually but I have only the references here, and anecdotal evidence to support the statement.
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    Re: I'm assuming there's no chance the CYA dropped like that

    If the CYA level measurement hasn't changed since Monday, is it OK to assume it's not going to even though it's been less than a week since I added? I'd like to add more as it's still shwoing as under 20ppm.
    15K gal, IG plaster, 3/4 HP pump, Pentair CCP320 320 sqft cartridge filter, Letro Legend cleaning robot

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    Re: I'm assuming there's no chance the CYA dropped like that

    I would not add more to my pool yet. The risk is that you overshoot your CYA target and have to do a partial drain of the pool to lower CYA. What is the hurry? There are about 10 people posting that you should wait a week after adding. Is there a reason why you don't want to wait and keep asking?
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    Re: I'm assuming there's no chance the CYA dropped like that

    I probably do need to be more patient. My pool is in need of a SLAM and I figured that balancing the CYA was a prerequisite to doing that, so that's part of the urgency. That said, I'm trying to keep the pH and chlorine at normal levels in the mean time, so hopefully my algae problems don't get worse while the CYA rises.

    EDIT: I'm glad you asked because my reply prompted me to re-read the SLAM prerequisites and I realized I've got it backwards. A lower CYA makes it easier to SLAM (less chlorine anyway). I had been figuring it would be harder to maintain the high level without stabilizer, but I forgot the stabilizer means you need a higher level anyway.
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    Re: I'm assuming there's no chance the CYA dropped like that

    For a SLAM you can "assume" the CYA level targeted is actually in the water. In your case I think you started at 0 and targeted 20, so assume 20 and start your SLAM.

    Re-test CYA at the one week point and adjust your FC for the SLAM at the tested level.

    Now, you don't have a location in your profile, so I'm shooting from the hip, but you do want 30-40 CYA for a SLAM in most locations to keep from loosing your FC during the day. If it were not for the UV of the spun consuming chlorine then zero CYA would be great for a SLAM.
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    Re: I'm assuming there's no chance the CYA dropped like that

    I'm in Northern California, so sun is definitely an issue. With that in mind, should I wait until the CYA is a bit higher? I only targeted 20 initially because it was reading essentially zero and I wasn't sure I trusted the measurement and didn't want to overshoot.
    15K gal, IG plaster, 3/4 HP pump, Pentair CCP320 320 sqft cartridge filter, Letro Legend cleaning robot

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    Re: I'm assuming there's no chance the CYA dropped like that

    Quote Originally Posted by kcbaltz View Post
    I'm in Northern California, so sun is definitely an issue. With that in mind, should I wait until the CYA is a bit higher? I only targeted 20 initially because it was reading essentially zero and I wasn't sure I trusted the measurement and didn't want to overshoot.
    Don't delay! If the pool is greenish, kill it before it grows worse! You only want CYA to be in the 30-40 range while doing the SLAM. If you need to add a bit more, do it, but don't wait for it to dissolve before you start the bleach. You can raise it afterwards easy enough. But kill that algae. Once the water gets warm, it takes off.
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    Mod Squad pooldv's Avatar
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    Re: I'm assuming there's no chance the CYA dropped like that

    Good, glad you reread that and didn't add more. I would add 10 ppm CYA in a sock, adjust ph to 7.2-7.4 and assume you have CYA of 30 until a test tells you otherwise next week. Start the slam. Check fhe Chlorine CYA Chart which says that shock level is 12 and get the FC up to 12 asap and keep it there as often as you can, up to every couple of hours, and at least twice per day.

    Good luck! Keep us posted, keep a record of your daily and overnight chlorine usage to verify you are making progress.
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    Re: I'm assuming there's no chance the CYA dropped like that

    Just got started today. pH is around 7.8, FC at 4.5. I added 128oz of 10%.

    FYI, the water is nice and clear, it's the yellow algae on the sides that concerns me. Some of it won't come off even with a wire brush.
    15K gal, IG plaster, 3/4 HP pump, Pentair CCP320 320 sqft cartridge filter, Letro Legend cleaning robot

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    Mod Squad pooldv's Avatar
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    Re: I'm assuming there's no chance the CYA dropped like that

    Alright, let's kill some algae!
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    Re: I'm assuming there's no chance the CYA dropped like that

    Very much so. My first 2 winters that happened to me. But last year my pool chemistry was a finely-honed machine before closing (not so the previous years). When I opened this year, I still had a little chlorine and the CYA was right where it was last year.

    FWIW, I found that CYA at around 50-60, which is lower than the regular recommended here, works best for me. Classic "Your mileage may vary"
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    Re: I'm assuming there's no chance the CYA dropped like that

    OK, I just performed the OCLT and FC was at 11, so I only lost 1ppm, which I think means I'm done by the usual definitions (no CC, OCLT < 1.0ppm, water clear). However, I've still got yellow staining on the plaster. I had thought maybe it was mustard algae because it was more tenacious than usual, but the description in the pool school talks about mustard algae forming clumps on the surface and I haven't seen that. The closest I've see is brownish "dirt" loose on the floor of the pool that is easily brushed away. I'm thinking to keep the SLAM going one more day and try brushing down the plaster again.
    15K gal, IG plaster, 3/4 HP pump, Pentair CCP320 320 sqft cartridge filter, Letro Legend cleaning robot

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