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

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Gig103

0
Jun 2, 2014
53
Phoenix, AZ
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!
 
:wave: 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.
 
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)
 
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. :D
 
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?
 
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!
 
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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?
 
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?
 

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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
 
jblizzle said:
Did you ever do the diluted CYA test starting with half pool and half tap water and doubling the reading?
Click to expand...

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
 
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rick6668 said:
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?
Click to expand...

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.
 
Gig103 said:
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.
Click to expand...

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.
 
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 :)
 
Gig103 said:
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 :)
Click to expand...

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.
 
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.
 

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