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Thread: CYA high, algae not clearing, should I drain the pool?

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    CYA high, algae not clearing, should I drain the pool?

    Hi all,

    I'm going on year 5 of pool ownership and I've had algae before. Usually it clears up with some heavy shocking and brushing, but this time nothing is doing it, so I am finally registering after reading some TFP searches in the past. The big problem I think I have is that my CYA is more than 100, so the SLAM process wants me to get my FC Up to 39ppm, and I'm not successful in keeping it that high. I even tried the 3% copper which worked in the past for me, and it's still green.

    I don't have the accurate test kit yet, nobody local sells it, but every day I was able to read my levels on my normal DPD (so under 5ppm) and I'd add more per the calculator. Last night I put in 4 gallons of 8.25% Clorox and this morning the FC was reading 3ppm and pH is up to 8.0 (it was 7.5 when I started Friday night). I only had 2 gallons to add before work. So question one is: Did I just go backwards since I won't be home until 6pm to add more?

    Question 2 is: should keep on pumping money into chemicals, or if I should invest in draining half my pool to get the CYA down? It's a 12k gallon Pebbletek pool in Phoenix, AZ, with the weekly high/low temps looking like this:
    111/74; 109/72; 110/71; 110/71

    I feel like #2 is the better option since it fixes a root cause, but it might be risky? I'd be starting around sundown (as to not be up all night) so the temps would still be in the 90s I suspect.

    Thanks for all the help from my past searches and for this too!

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    Mod Squad jblizzle's Avatar
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    Re: CYA high, algae not clearing, should I drain the pool?

    Welcome to TFP!!!

    If you want to take control, then you are going to have to invest in one of the Recommended Test Kits.

    If your CYA is truly over 100ppm, then it really would be best to replace water to get the CYA to a reasonable level and then follow the SLAM Process correctly.

    You can either drain and fill quickly over night to avoid too much exposure to the intense sun/heat or you could drain from the top while refilling at the bottom. The second method is slower and will require more water, but it is the safest option.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: CYA high, algae not clearing, should I drain the pool?

    Thanks JB. I called TFTestkits to ask about 2-day shipping, and while on the line Dave walked me through some preventative measures I could take until my test kit arrives, as well as a way to do a simultaneous drain/refill without wasting "too much" water. That was a lot of help so I bought their kit instead of the Taylor (Amazon Prime)

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    Re: CYA high, algae not clearing, should I drain the pool?

    Thanks for those nice words, Gig103. Your kit DID make today's USPS Priority mail shipment. I hope it gets to you on Wednesday.....then post up those test results and we'll all help get your pool crystal clear.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: CYA high, algae not clearing, should I drain the pool?

    Hi again folks,

    My pump and TF-50 test kit arrive today (Wednesday), and in the mean time I've been trying to get the pH to a good point. I just put in some 20% Muratic acid per the calculator and seem to have over compensated. I'm reading approx 7.2 now. If I'm going to pump out half my water to lower my CYA, what will this likely accomplish with respects to my pH? Should I try to bring it up a touch tonight, or not worry until after the water change-out?
    ~12,000 gallon IG pebble pool. Pentair CnC Plus 4-cartridge system, AO Smith 1.5hp single speed

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    Mod Squad jblizzle's Avatar
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    Re: CYA high, algae not clearing, should I drain the pool?

    If you are going to be dumping water, I would not bother adding anything to the pool at this point.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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    Re: CYA high, algae not clearing, should I drain the pool?

    Time for my daily check-in for some advice. The submersible pump is running, but I measured it at roughly 5gpm. My hose is returning at a little less, so I do see that in the past 3 hours the overall level has dropped. At 5gpm, to do a 60% water change (assuming total replacement, which isn't the case) I will be at 24 hours.

    To avoid damage to the pool (as the level is dropping fast and might dip below the tile soon), I don't think I should run it all night and day while I'm not around to monitor it. That means that I'll only be about 12% replacement when I go to bed, and up to another 20% replacement tomorrow while at work.

    That boils down to this question -- do I start my SLAM tomorrow night (~30% replaced so CYA around 70), or keep exchanging water another night and start the SLAM Friday night when the CYA will be better? If it helps make the determination, I can see the popups through the cloudy water so it isn't nearly as bad as when I started my TFP reading.

    Thanks again!
    Last edited by Gig103; 06-05-2014 at 12:25 AM. Reason: Clarity regarding phrase pump
    ~12,000 gallon IG pebble pool. Pentair CnC Plus 4-cartridge system, AO Smith 1.5hp single speed

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    Mod Squad jblizzle's Avatar
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    Re: CYA high, algae not clearing, should I drain the pool?

    I would finish lowering the CYA. Can you add a second hose to equalize the flow?
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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    Re: CYA high, algae not clearing, should I drain the pool?

    Unfortunately, no additional hose or hose bib I could use. I could turn on the auto-leveler, but it returns near the top and on the same side of the pool as the sump pump. I guess that would at least keep the water at the tile, I had turned off the leveler for that reason, but maybe keeping the concrete covered is better than the water waste?
    ~12,000 gallon IG pebble pool. Pentair CnC Plus 4-cartridge system, AO Smith 1.5hp single speed

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    Re: CYA high, algae not clearing, should I drain the pool?

    Update: The leveler did its job of keeping the water at the tile overnight, and while I might be pumping some of that water out I'm protecting the pebbletek.

    I will do my first CYA test tonight - how long would you recommend I run the pump to circulate the water before testing to get accurate readings, so I SLAM appropriately?
    ~12,000 gallon IG pebble pool. Pentair CnC Plus 4-cartridge system, AO Smith 1.5hp single speed

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    Mod Squad jblizzle's Avatar
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    Re: CYA high, algae not clearing, should I drain the pool?

    Circulate for at least 30 minutes. Realize that after you mix things up, you will have to remove a larger amount or water to get further CYA reductions.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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    Re: CYA high, algae not clearing, should I drain the pool?

    Well this is disheartening. After pumping water for 23 hours, then circulating the water for an hour to get an accurate reading, the CYA still reads more than 100. Seriously > 100 too, like below where it says "CYA" on the Taylor graduated cylinder.

    Other numbers
    FC = 17.5
    CC = 0.5
    pH = 7.8 (this was 7.2 last night before the water drain/refill)
    Calcium Hardness = 260
    Total Alkalinity = 175
    ~12,000 gallon IG pebble pool. Pentair CnC Plus 4-cartridge system, AO Smith 1.5hp single speed

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    Mod Squad jblizzle's Avatar
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    Re: CYA high, algae not clearing, should I drain the pool?

    Did you ever do the diluted CYA test starting with half pool and half tap water and doubling the reading?
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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    Re: CYA high, algae not clearing, should I drain the pool?

    Quote Originally Posted by jblizzle View Post
    Did you ever do the diluted CYA test starting with half pool and half tap water and doubling the reading?
    No, I hadn't heard about that. Do I dilute the 14mL post-mix with tap water, or do I start with half-tap, half-pool, with a full amount (7mL) of reagent?

    Edit: I finally found something. It looks like it's a full amount of reagent and only the pool water is diluted, per this thread
    Last edited by Gig103; 06-06-2014 at 02:05 AM. Reason: Kept searching
    ~12,000 gallon IG pebble pool. Pentair CnC Plus 4-cartridge system, AO Smith 1.5hp single speed

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    Re: CYA high, algae not clearing, should I drain the pool?

    Post up those results for the diluted CYA test so we can see where you are at.
    Do not add anything else to your water until you get the CYA at a level you want.
    Do you know what level you are shooting for?
    Rick
    Installed June 2012 Aqua Leader 24ft Round AG Influence w/54 inch walls 13,500 gallons
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    Re: CYA high, algae not clearing, should I drain the pool?

    Quote Originally Posted by rick6668 View Post
    Post up those results for the diluted CYA test so we can see where you are at.
    Do not add anything else to your water until you get the CYA at a level you want.
    Do you know what level you are shooting for?
    Hi Rick,

    I understand I am targeting a CYA of 40. I brought a 50/50 water sample to the pool store on my way to work this morning after continuing the water exchange overnight. I did not circulate the pump first, so this value is probably not too accurate, but they read it at 50, meaning that it's gone to approx 100 from my 100+ overnight. I have decided to keep draining until at least tonight if not tomorrow morning, then circulate and retest with my kit.
    ~12,000 gallon IG pebble pool. Pentair CnC Plus 4-cartridge system, AO Smith 1.5hp single speed

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    Re: CYA high, algae not clearing, should I drain the pool?

    Quote Originally Posted by Gig103 View Post
    Hi Rick,

    I understand I am targeting a CYA of 40. I brought a 50/50 water sample to the pool store on my way to work this morning after continuing the water exchange overnight. I did not circulate the pump first, so this value is probably not too accurate, but they read it at 50, meaning that it's gone to approx 100 from my 100+ overnight. I have decided to keep draining until at least tonight if not tomorrow morning, then circulate and retest with my kit.
    Just so you know, I wouldn't trust the pool store results at all. They are notoriously wrong, especially with the CYA test. I see you are going to retest with your kit, so good. You will know where you stand then.
    Rick
    Installed June 2012 Aqua Leader 24ft Round AG Influence w/54 inch walls 13,500 gallons
    Cartridge Filter 100SF, 1.5HP
    Aqua Plus Smarte System - In for vacations, BBB all the way.
    Love my PVC Solar Cover Hangers

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    Re: CYA high, algae not clearing, should I drain the pool?

    Wow I feel like I'm on a losing battle. By my calculation I've pumped out about 20k gallons into the yard from a 12k pool. I knew there would be losses while refilling but I did so from the opposite end, cool water pumping into the bottom. My CYA is down, but still reading 100 according to the carefully diluted Taylor test (NOT the pool store this time).

    FC = 6.5
    PH = 7.7
    CYA = 100
    TA = 175
    CH = 225

    I have noticed that the water doesn't have a trace of green anymore. The water is not clear, but doesn't look unusual for my pool (I never have crystal clear water because I'm new to TFP!) I can't decide if I should still SLAM at 39ppm FC, or just get my FC to normal (12ppm for this CYA) and try an overnight free chlorine test. I will be bringing the pH down while I wait for responses
    ~12,000 gallon IG pebble pool. Pentair CnC Plus 4-cartridge system, AO Smith 1.5hp single speed

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    Re: CYA high, algae not clearing, should I drain the pool?

    Quote Originally Posted by Gig103 View Post
    Wow I feel like I'm on a losing battle. By my calculation I've pumped out about 20k gallons into the yard from a 12k pool. I knew there would be losses while refilling but I did so from the opposite end, cool water pumping into the bottom. My CYA is down, but still reading 100 according to the carefully diluted Taylor test (NOT the pool store this time).

    FC = 6.5
    PH = 7.7
    CYA = 100
    TA = 175
    CH = 225

    I have noticed that the water doesn't have a trace of green anymore. The water is not clear, but doesn't look unusual for my pool (I never have crystal clear water because I'm new to TFP!) I can't decide if I should still SLAM at 39ppm FC, or just get my FC to normal (12ppm for this CYA) and try an overnight free chlorine test. I will be bringing the pH down while I wait for responses
    I would drain and refill again, CYA of 100 will be very hard to SLAM and maintain. You need to get that CYA down to 50 at least.
    Not what you wanted to hear, I know.
    Rick
    Installed June 2012 Aqua Leader 24ft Round AG Influence w/54 inch walls 13,500 gallons
    Cartridge Filter 100SF, 1.5HP
    Aqua Plus Smarte System - In for vacations, BBB all the way.
    Love my PVC Solar Cover Hangers

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    Mod Squad jblizzle's Avatar
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    Re: CYA high, algae not clearing, should I drain the pool?

    So you measured 50ppm and then doubled to get 100ppm? I would suggest doing a drain and fill over night ... even 25% would drop your CYA to a reasonable level.

    Then you should raise the FC up to SLAM level and do the OCLT ... does not sound like you water is what we would call crystal clear.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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