Rapidly dropping CYA... consistently green and cloudy pool

[AZ Devil Dawg]

I'm new to the site and relatively new to pools, but am already learning a lot.

I have somewhere between a 10k-12k gallon plaster pool and am in Phoenix AZ. I'll start by saying I have been using only test strips and my local pool store (which was just bought out by Leslies) for testing, though just purchased my own test kit. Anyways, for the past year my CYA readings were high but consistent. However it suddenly dropped to 5. The initial feedback was I have a leak, though I do not have an auto fill so I feel I would notice if I were refilling THAT much. Another guy with seemingly more experience told me he disagrees it is a leak, since my TDS is still high and usually in a leak these two decrease together. He sold me some conditioner granules which I added throughout the day last Saturday. I shocked that night as the pool was green, then waited. Monday, I went back for a test and my CYA was reading in the 30s. Yay. However, by Friday my pool was looking greenish again so I went in to check my chlorine levels. My chlorine was certainly low, but to my surprise my CYA was back at 5. This was using Leslies testing meter. The guy was so surprised he opened a new test kit to confirm, which also read barely any CYA.

Obviously common knowledge is that CYA can only reduce as a result of water replacement, but I did not backwash or add any new water between reading at 30 and reading at 5. I stumbled upon a few posts here that mentioned perhaps algae or something can consume CYA or convert is to bacteria? but I'm unsure what to do now. It seems the SLAM process is recommended, but how do I do this without first getting my CYA back in range? Any ideas or suggestions are appreciated, I'm confused and lost.

 

[dfwnoob]

Welcome to TFP! Looks like you've got a couple things going on there.

Unfortunately, you're getting Pool Stored. Stay out of Leslie's, stop letting them test your water, and ESPECIALLY stop letting them sell you unnecessary miracle potions that don't work. The CYA test is one of the most notoriously incorrect tests for pool stores, and as a general rule, we don't give advice based on pool store testing. Not that it's really relevant here, but TDS is an entirely meaningless metric and is the only thing it really measures is how much money a pool store can liberate from your wallet.

Which test kit did you purchase? If it wasn't a Taylor K-2006/K-2006C (the C is preferred) or a TFTestKits TF-100/TF-Pro, please return it as these are the only two test kits recommended for the TFP method. They are tried and true and include all of the necessary tests you'll perform on the way to fixing your water chemistry issues.

It's very likely your water is turning green due to insufficient sanitizer (chlorine) compared to the amount of CYA, especially if you've been relying on Guess Strips up to this point. How are you chlorinating your pool?

You can't SLAM the pool because you don't know your CYA and you don't have a test kit with the FAS-DPD chlorine test yet.

For now, I would stop adding any more magic Leslie's potions to your pool until you get your test kit and we can go from there.

It's important to understand the FC/CYA ratio: Chlorine / CYA Chart

And if you haven't already, start reading through the ABCs of Pool Water Chemistry (and the rest of Pool School too!): ABC's of Pool Water Chemistry

 

[AZ Devil Dawg]

Welcome to TFP! Looks like you've got a couple things going on there.

Unfortunately, you're getting Pool Stored. Stay out of Leslie's, stop letting them test your water, and ESPECIALLY stop letting them sell you unnecessary miracle potions that don't work. The CYA test is one of the most notoriously incorrect tests for pool stores, and as a general rule, we don't give advice based on pool store testing. Not that it's really relevant here, but TDS is an entirely meaningless metric and is the only thing it really measures is how much money a pool store can liberate from your wallet.

Which test kit did you purchase? If it wasn't a Taylor K-2006/K-2006C (the C is preferred) or a TFTestKits TF-100/TF-Pro, please return it as these are the only two test kits recommended for the TFP method. They are tried and true and include all of the necessary tests you'll perform on the way to fixing your water chemistry issues.

It's very likely your water is turning green due to insufficient sanitizer (chlorine) compared to the amount of CYA, especially if you've been relying on Guess Strips up to this point. How are you chlorinating your pool?

You can't SLAM the pool because you don't know your CYA and you don't have a test kit with the FAS-DPD chlorine test yet.

For now, I would stop adding any more magic Leslie's potions to your pool until you get your test kit and we can go from there.

It's important to understand the FC/CYA ratio: Chlorine / CYA Chart

And if you haven't already, start reading through the ABCs of Pool Water Chemistry (and the rest of Pool School too!): ABC's of Pool Water Chemistry

I have learned very quickly that Leslies is not the answer. I don't use their products but had been relying on them for testing. They keep selling me conditioner instead of trying to root cause the issue, so I ordered the TF-100.

Because of reported high CYA, I had not been floating Trichlor tabs, but started again this past week to try to keep some CYA in the water. Otherwise, I had been shocking weekly with 73% cal hypo. However lately its as if I can't keep up... the green creeps in a day or two after the water is cleared. Last week I tried adding two pounds of sodium dichlor for the stabilizer as well.

Should I just let the water sit and get more swampy until the test kit gets here? Last I went in to the pool store, the guy did do a manual test with reagent which barely read any CYA in the water.

 

[mknauss]

I had been shocking weekly with 73% cal hypo.

Using Cal Hypo in a pool in our climate and fill water conditions is a crime. Your fill water is already 250 ppm CH. The last thing you need to do is add more calcium. Please use sodium hypochlorite aka liquid chlorine.

If you truly dropped the CYA that much, and did not exchange water, I suspect the water has ammonia in it, and that is why the chlorine is consumed quickly.

Ammonia - Further Reading

www.troublefreepool.com

 

[AZ Devil Dawg]

Using Cal Hypo in a pool in our climate and fill water conditions is a crime. Your fill water is already 250 ppm CH. The last thing you need to do is add more calcium. Please use sodium hypochlorite aka liquid chlorine.

If you truly dropped the CYA that much, and did not exchange water, I suspect the water has ammonia in it, and that is why the chlorine is consumed quickly.

Ammonia - Further Reading

www.troublefreepool.com

Interesting... I was told by the store that cal hypo is way more effective than liquid chlorine... Any recommendations where to start sourcing liquid chlorine?

I'm intrigued by the bacteria/ammonia angle. It just makes sense to me as a root cause. I started looking for an ammonia test today, and once my TF-100 gets here I will be able to accurately test my CYA. How do I proceed with the SLAM if I cannot raise my CY though?

 

[mknauss]

Read the Ammonia article I linked -- it describes how to clear the pool of ammonia.

Chlorine is chlorine, it all depends on how you deliver it. Cal Hypo adds calcium, the last thing you need is calcium. Sodium Hypochlorite adds, water. Both add the same chlorine.

In Phoenix, I believe there are HASA dealers. They sell 12.5% sodium hypochlorite aka liquid chlorine aka pool shock, etc. in refillable containers. Otherwise Walmart Pool Essentials or Home Depot HDX brands.

 

[AZ Devil Dawg]

I'll head to Home Depot today. Perhaps a silly question...they say to add shock at sundown to prevent UV rays from zapping it. Is liquid chlorine the same, and should I start the SLAM at sundown? Or can I perform during the day?

 

[mknauss]

You can SLAM 24/7 as you are to have 30 ppm CYA in the water.

Right now, until you get your test kit, it is best to add 5 ppm FC worth of liquid chlorine in the evening with the pump off.