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Thread: How low can CYA go?

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    How low can CYA go?

    I just opened up my pool. It is a green algae cesspool.

    So I have started to SLAM (as best I can, EDIT: What I mean by that is that I can keep shock levels but I do have to go to work so occasionally it will dip down to below shock and then I will keep it shocked all through the night and most of the day - this weekend I will continue to keep it shocked continuously).

    My last reading (TF-100) was:

    CYA = 35
    FC = 16, CC = 0
    ph = 7.2

    I noticed because I have to backwash my DE filter a lot, my CYA is gradually going lower (it was 40 which is why I wanted FC to hit 16).

    Question, how low can CYA go before I need to restore it? How do you normally restore CYA?

    I do have a few Pool Logic TriChlor tablets I could throw into the skimmer which I assume would slowly raise my CYA count.

    EDIT: Wait a minute, you can buy stabilizer. That was a dumb question. Sorry. And it looks like 20 ppm is the lower threshold based on the pool school chart. Man, I am having an off day.

    Anyway, the pool HAS been getting back to blue after 3 straight days of SLAM (it's green again because I wiped the floor a little to break up the green algae bloom).
    20x40 L-shape 35k gallons, Pentair FNS 60 SQFT DE Filter, Pentair Multi-port Valve, Hayward Super Pump w/1 glorious HP, Vinyl Liner, Dolphin Z5, TF-100 w/Speed Stir

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    Re: How low can CYA go?

    It is best to keep it above 30. Keep brushing as this really helps.
    Lisa
    Intex AG vinyl 15' x 48" 4,300 gallons due to skimmer install, Krystal Clear SF pump combo 2800 GPH, Krystal Clear SWG, Pool Blaster Max vacuum, Hayward thru the wall skimmer, TF 100 test kit with speed stir, K 1766 Taylor salt test, My SLAM Process

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    Re: How low can CYA go?

    Below 30 you'll want to add more CYA. If you have pucks, use 'em. Just know that they dissolve slowly. If you want to bring it up fast while you're doing the SLAM, buy some dichlor powder and use it in place of bleach for a few doses until it's used up. Every pound package of dichlor in your pool will add 1.9 FC and 1.7 CYA, so 3 bags will add 5 CYA. Don;t buy a whole big bucket of the stuff!

    If you're still seeing green, you need to really scrub things with the brush. Algae grows a slimy scab to protect itself. Brushing breaks that off and exposes the algae to bleach so you can kill it.
    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: How low can CYA go?

    Thanks guys. I am using calcium hypo 73% bags of shock.

    Can I buy stabilizer from my local pool store and just dump a small amount (like <1 quart, whatever PoolMath tells me)?

    Last year I inherited the pool with like a CYA of 140ish at the end of the season which ruined it for me. This year I am absolutely bent on keeping my CYA 30-50!
    20x40 L-shape 35k gallons, Pentair FNS 60 SQFT DE Filter, Pentair Multi-port Valve, Hayward Super Pump w/1 glorious HP, Vinyl Liner, Dolphin Z5, TF-100 w/Speed Stir

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    Re: How low can CYA go?

    Quote Originally Posted by pisymbol View Post
    Thanks guys. I am using calcium hypo 73% bags of shock.

    Can I buy stabilizer from my local pool store and just dump a small amount (like <1 quart, whatever PoolMath tells me)?

    Last year I inherited the pool with like a CYA of 140ish at the end of the season which ruined it for me. This year I am absolutely bent on keeping my CYA 30-50!
    Yes, you can add straight CYA.

    If you're using Cal-hypo, be aware that a vinyl pool can still grow scale with high CH readings, same as a plaster pool. And you can't use a steel brush to loosen it, either. A fifty pound bucket of Cal-hypo 73% in your 35,000 gallon (That's HUGE) pool will raise CH by 87. Be careful. The only way to get rid of excess CH is draining and refilling, which messes up all the other chemistry, too.
    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: How low can CYA go?

    Quote Originally Posted by Richard320 View Post
    Yes, you can add straight CYA.

    If you're using Cal-hypo, be aware that a vinyl pool can still grow scale with high CH readings, same as a plaster pool. And you can't use a steel brush to loosen it, either. A fifty pound bucket of Cal-hypo 73% in your 35,000 gallon (That's HUGE) pool will raise CH by 87. Be careful. The only way to get rid of excess CH is draining and refilling, which messes up all the other chemistry, too.
    Wait a minute...I thought CH did not effect a vinyl liner at all (from 0 - 350 it would be fine). Why is that not so?

    So now I'm lost again...darn it, I thought I had this. If not calcium hypo, what should I use? I was trying to avoid di and tri-chlor derivatives since they seem to raise CYA unnecessarily (and I need to continually SLAM the pool for a few more days). i used cal hypo exclusively last year with no real issue I could detect.

    Btw, can I test CH while in SLAM? I just dumped a bag in it to raise the FC count to 16-17 again (it was sitting at 15).

    I'm thinking I should stick to sodium hypo which I believe just adds a little salt in addition to raising FC (now I have to see if my local guy has it).
    20x40 L-shape 35k gallons, Pentair FNS 60 SQFT DE Filter, Pentair Multi-port Valve, Hayward Super Pump w/1 glorious HP, Vinyl Liner, Dolphin Z5, TF-100 w/Speed Stir

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    Re: How low can CYA go?

    Quote Originally Posted by pisymbol View Post
    Wait a minute...I thought CH did not effect a vinyl liner at all (from 0 - 350 it would be fine). Why is that not so?

    So now I'm lost again...darn it, I thought I had this. If not calcium hypo, what should I use? I was trying to avoid di and tri-chlor derivatives since they seem to raise CYA unnecessarily (and I need to continually SLAM the pool for a few more days). i used cal hypo exclusively last year with no real issue I could detect.

    Btw, can I test CH while in SLAM? I just dumped a bag in it to raise the FC count to 16-17 again (it was sitting at 15).
    Yes, you can test CH during the SLAM.

    Low CH is not a problem for a vinyl pool. High CH is a problem for any pool. Testing is the only way to know where you are.

    It might do to reread How to Chlorinate your pool again.
    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: How low can CYA go?

    Quote Originally Posted by Richard320 View Post
    Yes, you can test CH during the SLAM.

    Low CH is not a problem for a vinyl pool. High CH is a problem for any pool. Testing is the only way to know where you are.

    It might do to reread How to Chlorinate your pool again.

    It's between 300 and 350ppm according to my TF-100 (I checked it three times).

    So that seems fine (I even have some buffer room). My TA though is 150-160 which is a little high (not sure if that's valid during a SLAM).

    The problem with the "How to Chlorinate Your Pool" article is that it doesn't really spell out what chemicals raise what in addition to their main use (so hypo raises FC, yes I know that, but I didn't realize it raise CH that much too).

    I edited the wrong post, I should have picked up sodium hypo instead. I believe that has no real adverse side effect other than adding a little salt, correct?

    (Btw, I'm using 1 pound bags, I have 7 left. I think I can use them without causing a problem with CH (since I'm backwashing too). Do you agree?

    Thanks Richard, I really appreciate the help. This is my first official season (can you tell?)
    20x40 L-shape 35k gallons, Pentair FNS 60 SQFT DE Filter, Pentair Multi-port Valve, Hayward Super Pump w/1 glorious HP, Vinyl Liner, Dolphin Z5, TF-100 w/Speed Stir

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    Re: How low can CYA go?

    Quote Originally Posted by pisymbol View Post
    It's between 300 and 350ppm according to my TF-100 (I checked it three times).

    So that seems fine (I even have some buffer room). My TA though is 150-160 which is a little high (not sure if that's valid during a SLAM).

    The problem with the "How to Chlorinate Your Pool" article is that it doesn't really spell out what chemicals raise what in addition to their main use (so hypo raises FC, yes I know that, but I didn't realize it raise CH that much too).
    I've never heard of dry Sodium Hypochlorite. But if it's real, all it will leave behind is salt.

    Down near the bottom of poolmath it will tell you Effects of Adding Chemicals. It shows what side effects each chemical has. The pH calculation is a rough estimate and is only good for small adjustments. Be sure you enter your pool volume at the top first.

    High TA is no big deal. It will come down over time when you adjust pH. You might notice the target is 70-90+. If you're raising, you need a target number to calculate dose. If you're above it, just plug in the current number as the target and move on. It's just dissolved baking soda, it's not harmful to humans at all. People brush their teeth with it!
    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: How low can CYA go?

    Quote Originally Posted by Richard320 View Post
    I've never heard of dry Sodium Hypochlorite. But if it's real, all it will leave behind is salt.
    Oh, I might be confused with another baggage. So basically if I want just sodium hypochlorite, it's liquid. Ok.

    Down near the bottom of poolmath it will tell you Effects of Adding Chemicals. It shows what side effects each chemical has. The pH calculation is a rough estimate and is only good for small adjustments. Be sure you enter your pool volume at the top first.
    But it doesn't say how much it will add.

    High TA is no big deal. It will come down over time when you adjust pH. You might notice the target is 70-90+. If you're raising, you need a target number to calculate dose. If you're above it, just plug in the current number as the target and move on. It's just dissolved baking soda, it's not harmful to humans at all. People brush their teeth with it!

    LOL. Do you think I could get away with using the last of my cal-hypo (7 pounds) without any ill effects? (again I will need to backwash at least 3 times because of the green algae)

    Btw, Richard, if I start using liquid chlorine, is that the equivalent of bleach in PoolMath (just change % by weight)?
    20x40 L-shape 35k gallons, Pentair FNS 60 SQFT DE Filter, Pentair Multi-port Valve, Hayward Super Pump w/1 glorious HP, Vinyl Liner, Dolphin Z5, TF-100 w/Speed Stir

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    Richard320's Avatar
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    Re: How low can CYA go?

    Originally Posted by Richard320
    I've never heard of dry Sodium Hypochlorite. But if it's real, all it will leave behind is salt.
    Oh, I might be confused with another baggage. So basically if I want just sodium hypochlorite, it's liquid. Ok.

    Down near the bottom of poolmath it will tell you Effects of Adding Chemicals. It shows what side effects each chemical has. The pH calculation is a rough estimate and is only good for small adjustments. Be sure you enter your pool volume at the top first.
    But it doesn't say how much it will add.
    It most certainly does! If you tell it the volume up top and then go down and enter a quantity of some chemical, it will tell you how much it will raise whatever and how much it will mess up pH.

    High TA is no big deal. It will come down over time when you adjust pH. You might notice the target is 70-90+. If you're raising, you need a target number to calculate dose. If you're above it, just plug in the current number as the target and move on. It's just dissolved baking soda, it's not harmful to humans at all. People brush their teeth with it!
    LOL. Do you think I could get away with using the last of my cal-hypo (7 pounds) without any ill effects? (again I will need to backwash at least 3 times because of the green algae)

    Btw, Richard, if I start using liquid chlorine, is that the equivalent of bleach in PoolMath (just change % by weight)?
    Yes, use it up. Good thing you didn't just get a fresh bucketfull, huh? Bleach, Liquid Shock, Pool Chlorine, whatever they call it, is just Sodium Hypochlorite. It'll say the strength on the jug somewhere. Just enter that. If they don't give it, don't buy it. They're ashamed to tell you how diluted it is, lest you figure out how expensive that water inside is.
    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: How low can CYA go?

    Quote Originally Posted by Richard320 View Post
    It most certainly does! If you tell it the volume up top and then go down and enter a quantity of some chemical, it will tell you how much it will raise whatever and how much it will mess up pH.

    Yes, use it up. Good thing you didn't just get a fresh bucketfull, huh? Bleach, Liquid Shock, Pool Chlorine, whatever they call it, is just Sodium Hypochlorite. It'll say the strength on the jug somewhere. Just enter that. If they don't give it, don't buy it. They're ashamed to tell you how diluted it is, lest you figure out how expensive that water inside is.

    These are my last six bags then. Tomorrow I am a sodium hypo man thanks to you Richard. I can see the bottom of my pool now...the SLAM is working...I was juat at FC 15 and I dumped a bag of shock to raise it to ~17 for the night SLAM. Hopefully when I wake up it will be somewhat blue again.

    Wow, I will double check the pool math calculator again.
    20x40 L-shape 35k gallons, Pentair FNS 60 SQFT DE Filter, Pentair Multi-port Valve, Hayward Super Pump w/1 glorious HP, Vinyl Liner, Dolphin Z5, TF-100 w/Speed Stir

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