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Thread: Opening levels and "high" CYA

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    Circles47's Avatar
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    Opening levels and "high" CYA

    Removed the winter pool cover the other day, to sparkling clean water! Without adding any chemicals, these were my numbers:

    FC - 4.4
    CC - 0.6
    PH - 7.7
    TA - 170 (need to aerate)
    CYA - 100
    CH - 200
    Water temp - 53 F

    Test kit is a Taylor - K-2006

    My question is this: I was a little unsure about my CYA testing, and think I may have added too many drops to get the black dot

    to disappear, and not sure the last several drops did anything at all. With my numbers as they are, especially the FC number, is

    it even possible that my CYA number is 100? Seems like if it was this high, my FC would have been around zero. Or, is it possible

    that the colder water temps affected my readings?
    Sharkline 24' round AG, 15,200 gal, vinyl liner, Hayward Power Flo Matrix 1-1/2 hp pump, Hayward S210T 200 lb.sand filter, Rheem 100 cfh heater

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    Re: Opening levels and "high" CYA

    The CYA test can read lower than actual if you do the test with very cold water. The sample should be allowed to warm up to room temperature before doing the test.

    If you think your CYA is close to 100, you might want to use 1/2 pool water & 1/2 tap water and then multiply the results by 2. This will help let you know if you are over 100.

    What was the CYA level before you closed the pool?

    TA - 170 (need to aerate)
    Aeration raises pH without affecting the TA. To lower the TA, you first use muriatic acid to lower the pH to about 7.2, then aerate to increase the pH. The whole process is in Pool School
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    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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    Re: Opening levels and "high" CYA

    Right. I wanted to give just enuf info that others would know that I understood the process, but looks like it had just the opposite effect!
    Sharkline 24' round AG, 15,200 gal, vinyl liner, Hayward Power Flo Matrix 1-1/2 hp pump, Hayward S210T 200 lb.sand filter, Rheem 100 cfh heater

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    Re: Opening levels and "high" CYA

    I'm not sure I understand your reference to FC and CYA relationship.

    Regardless, you can do the CYA test over and over. Simply pour the solution back into the squeeze bottle and start over putting it into the view tube. You could literally do that test 10 times using the same solution and then take the average of your readings as a fairly accurate CYA result.
    Dave S.
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    Re: Opening levels and "high" CYA

    I'm not sure I understand my own question either! For some reason, I had it in my head that high CYA all winter would result in FC levels of zero come opening time. Tested CYA again, still 100 no matter how I do it. Shocked it today and brought it up to 33.5 FC, while I decide what to do about my high CYA. No one ever told me that using chlorine tablets in the floater would add CYA, so last year I was loading up the floater with as many as I could fit in it, until I learned different. Should prob just bite the bullet and drain/refill the 40% that the pool calculator recommends, or........lots more chlorine until it gets splashed out.

    Why would you ever use the chlorine tablets if they just continue adding CYA to your water??
    Sharkline 24' round AG, 15,200 gal, vinyl liner, Hayward Power Flo Matrix 1-1/2 hp pump, Hayward S210T 200 lb.sand filter, Rheem 100 cfh heater

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    Re: Opening levels and "high" CYA

    I might also add, the guy at the pool store told me last year to add these chemicals every week:

    5 oz algaecide

    4 oz water clarifier (mixed up in 5 gal of water)

    1 gal. 10.5% chlorine

    And to also use the floating tablet chlorinator, although partway through the season, he told me to use no more than 1 puck at a time.

    I did this faithfully every week last year, had a sparkling clean pool, and opened up a sparkling clean pool this spring.

    If I continue this each week this year, what are the chances that I'll not have any issues until the CYA comes down through regular use?
    Sharkline 24' round AG, 15,200 gal, vinyl liner, Hayward Power Flo Matrix 1-1/2 hp pump, Hayward S210T 200 lb.sand filter, Rheem 100 cfh heater

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    Re: Opening levels and "high" CYA

    As previously recommended, did you test the CYA with 50/50 split of pool and tap water? Test mat show 100 when it is quite a bit higher. Just want you to know where you are starting from.

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    Re: Opening levels and "high" CYA

    Yes, I did. I brought a water sample inside, let it warm up a bit, and tested it as I had before. It was approx 100. I then did the 50/50 test, and it read about 50. Times 2 = 100

    I didn't have a real accurate way to test the CYA when I winterized the pool last year.
    Sharkline 24' round AG, 15,200 gal, vinyl liner, Hayward Power Flo Matrix 1-1/2 hp pump, Hayward S210T 200 lb.sand filter, Rheem 100 cfh heater

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    Re: Opening levels and "high" CYA

    Ok. Just wanted to be sure as others have though 100 and after the split test found they were over 150.

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    Jason, TFP Moderator
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    Re: Opening levels and "high" CYA

    Quote Originally Posted by Circles47
    Should prob just bite the bullet and drain/refill the 40% that the pool calculator recommends, or........lots more chlorine until it gets splashed out.
    Well, I suggest you do at least a 30% drain/refill and try to get the CYA to something reasonable. Your pool will be soooo much easier to maintain.

    Why would you ever use the chlorine tablets if they just continue adding CYA to your water??
    They can be saved and used when you go on vacation....maybe...if your CYA is low enough by then to make it a good idea

    Or your CYA may be low (at some point in the future!) and you want to raise it. You could use them then. Anyhoo, just save them because they are hard to kill....and will last a long, long time w/proper dry storage

    Your #'s look pretty good, except for the CYA. Get that under control and you should have smooth sailing this summer. No more algaecide or water clarifier as recommended by the pool store.

    Just good ole' bleach/liquid chlorine. Stick with TFP and your good test kit and your pool will be happy .
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    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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    Re: Opening levels and "high" CYA

    Well, thanks Butterfly! Guess I better start draining/refilling......not sure why it seems like such a task!
    Sharkline 24' round AG, 15,200 gal, vinyl liner, Hayward Power Flo Matrix 1-1/2 hp pump, Hayward S210T 200 lb.sand filter, Rheem 100 cfh heater

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    Re: Opening levels and "high" CYA

    I'll add to Butterfly's comment about pucks. I open my pool very early and usually open to Zero CYA. I use my pucks while the water is still too cold for chlorine or SWG until CYA is where I want it. After that, if water is still too cold, I'll use chlorine until water is at 70 degrees or better and then the SWG will kick in for the remaining part of the summer.
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    Re: Opening levels and "high" CYA

    Why would your CYA be zero at opening? I thot CYA remained until a water refill?
    Sharkline 24' round AG, 15,200 gal, vinyl liner, Hayward Power Flo Matrix 1-1/2 hp pump, Hayward S210T 200 lb.sand filter, Rheem 100 cfh heater

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    Re: Opening levels and "high" CYA

    Yesterday I shocked the pool up to 33.5 ppm FC, and 1 ppm CC, even though water was clear. This morning, shock levels were at 30 ppm FC, and .5 ppm CC. But......while the water was clear yesterday before shocking, this morning it was milky white...
    I can still see the bottom of the pool, but definitely cloudy. I can only assume that this is dead algae that was before unseen, and indicative of the issues that await me with high CYA. So.......beginning to dump.....
    Sharkline 24' round AG, 15,200 gal, vinyl liner, Hayward Power Flo Matrix 1-1/2 hp pump, Hayward S210T 200 lb.sand filter, Rheem 100 cfh heater

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    Re: Opening levels and "high" CYA

    Quote Originally Posted by Circles47
    Why would your CYA be zero at opening? I thot CYA remained until a water refill?
    Some people, including myself have experienced drops in CYA concentrations over the winter. To quote JasonLion:
    CYA is sometimes lost over the winter. It is believed that this is caused by anaerobic soil bacteria that can sometimes grow in pool water when the pool is covered and FC levels are zero.
    Quote Originally Posted by Circles47
    I can only assume that this is dead algae that was before unseen, and indicative of the issues that await me with high CYA. So.......beginning to dump.....
    Your high cya does not help you, so a drain/refill is a good idea. With that said, shocking is a process and since your FC was/is still dropping and you measured the 1 ppm of CC, you had algae regardless of water clarity, and what you are seeing today is just more dead algae. Water being clear is only one of the three criteria (and the last) since clear water by itself is not always a sign of no algae.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: Opening levels and "high" CYA

    Your high cya does not help you, so a drain/refill is a good idea. With that said, shocking is a process and since your FC was/is still dropping and you measured the 1 ppm of CC, you had algae regardless of water clarity, and what you are seeing today is just more dead algae. Water being clear is only one of the three criteria (and the last) since clear water by itself is not always a sign of no algae.
    Well, I'm slowly learning. I'm starting to see that proper pool care isn't really all that complicated, but rather it's us people who are great complicators! I surely appreciate all the sound and prompt counsel I've received on here.

    Dropped a sump pump in the pool, have lowered it about 16 inches so far....still about 10 to go. Better to do it now than to be doing it in the middle of swim season.......and having to endure the disapproval of the family!
    Sharkline 24' round AG, 15,200 gal, vinyl liner, Hayward Power Flo Matrix 1-1/2 hp pump, Hayward S210T 200 lb.sand filter, Rheem 100 cfh heater

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    Re: Opening levels and "high" CYA

    Hooray! After a massive dump/re-fill, my CYA is down from 100 to 35! I know that with it this low I'll have to keep an eye on it, but if I keep it at the lower end of the scale, I can add some tablets if we go on vacation without worrying about it.

    Here's my new numbers:

    FC - 7.4 (Because I had brought the pool up to shock level with the high CYA, it's still this high after the refill. I have not
    added any new chlorine.)
    CC - 0.4
    PH - 7.2
    TA - 250
    CYA - 35
    CH - 230

    I did add some metal sequestrant due to the well water re-fill, but we have pretty good water. Maybe .25 - .5 ppm iron.

    So.....Right now I'm aerating the pool to raise the PH to 7.8 or so, and then using muriatic acid to bring down the TA to more acceptable levels.

    I plan to test the FC again this evening, and also in the morning, and see if it's holding or not. If not, I'll shock it at that point. It seems from the CC level, that nothing much is happening.

    Is there anything I've missed??
    Sharkline 24' round AG, 15,200 gal, vinyl liner, Hayward Power Flo Matrix 1-1/2 hp pump, Hayward S210T 200 lb.sand filter, Rheem 100 cfh heater

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    Re: Opening levels and "high" CYA

    Yep, you got it under control. If you pass the OCLT, then as you said, you are good to go to maintenance chlorine and then hammer that TA down where you want it.

    Very nice job and this is for you

    okay now, we are wanting to see a pic
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    You're done SLAMing when:
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    Re: Opening levels and "high" CYA

    Is there anything I've missed??
    If you want to raise pH (I would leave yours alone), do so with 20 Mule team Borax.

    If you want to lower TA, do so by using the acid aeration method in Pool School
    Dave S.
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    Re: Opening levels and "high" CYA

    Thanks again for all the help and guidance! Here's the pic, in the midst of aeration.
    Attached Images Attached Images
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