Beautiful clean pool, but LOSING CYA AND FC

[CoveredPool]

I have a 14k gallon inground, covered pool. The water is crystal clear, and there is no visible algae. However, the pool will not hold chlorine, and I am losing CYA over time (without water changes).

Based on this article (poolsolutions.com...), I have been under the belief that some kind of bacteria is consuming my CYA. So, for the past couple weeks, I have been shocking the pool to 10ppm every night. When I tested this morning, it was at 5.5ppm. This demonstrates some progress, as almost all of the FC was being depleted overnight when I tested last week.
Is this being caused by bacteria (and so I should continue shocking pool every night)?

I'm wondering whether it could be something else. Like, the water maintains at 88-90 degrees. Could this temperature be somehow leading to the FC and CYA loss (as is suggested here: blog.orendatech.com...)? Obviously I'd prefer not to be wasting money on gallons and gallons of bleach, if the CYA and FC loss is inevitable at these temperatures.

PH is 7.6
CYA is in the 20s (was ~45, but I'm rapidly losing it over time)

Thanks!

 

[mknauss]

Welcome to the forum!
How are you testing your pool water chemistry?
CYA degradation to ammonia is well known here on TFP. But you do not have that. If you did, your FC would be zero after only a few minutes. You are holding some FC, so that is not your issue.
Warm water does increase the degradation of CYA up to about 10-15% per month.
Let us know how you are testing your pool water chemistry. And please post a full set of test results.
I suggest you read ABC's of Pool Water Chemistry.

 

[CoveredPool]

Welcome to the forum!
How are you testing your pool water chemistry?
CYA degradation to ammonia is well known here on TFP. But you do not have that. If you did, your FC would be zero after only a few minutes. You are holding some FC, so that is not your issue.
Warm water does increase the degradation of CYA up to about 10-15% per month.
Let us know how you are testing your pool water chemistry. And please post a full set of test results.
I suggest you read ABC's of Pool Water Chemistry.

Thanks! I'm using Taylor. As of this morning...

FC 5.5 (this was 10 last night when I shocked it)
PH 7.6
TA 90
CYA ~25 (this was >40 a few weeks ago)
Temperature 88 degrees

 

[mknauss]

From your member name, can I assume you have a covered pool? Is that an autocover, indoor pool, ???

Please fill out your signature.

You are not passing what we call an Overnight Chlorine Loss Test. That means you have algae. You need to follow the SLAM Process

 

[CoveredPool]

From your member name, can I assume you have a covered pool? Is that an autocover, indoor pool, ???

Please fill out your signature.

You are not passing what we call an Overnight Chlorine Loss Test. That means you have algae. You need to follow the SLAM Process

14k gallon / in ground / outdoor / auto cover (black)

I have been slamming every night. Does algae explain the CYA loss?

 

[mknauss]

Algae does not explain CYA loss. But your loss (40/50 to 30) is not all that significant over a period of time and elevated water temperatures.

You are not following the SLAM Process. I suggest you read the process and follow it to eliminate the algae in your pool water.

 

[CoveredPool]

If it was algae, wouldn't I be able to feel/see it? There's nothing...

 

[mknauss]

Not necessarily.

What Taylor kit are using? Please add that to your signature.