Where did my CYA go?

[Babe the Blue Ox]

Just opened the pool this weekend. 23,700 gallon above ground. Vinyl liner. Sand filter.

Current readings:
FC 3.5
CC 0.5
PH 7.5
TA 100
CYA <30

The CYA level was between 50 & 60 when I covered the pool last fall. I expected it to be about the same when I reopened. My test cylinder only reads to 30 and the dot on the bottom is still visible when the vial is full. My CYA level is likely closer to 20.

I didn't think this stuff went away. Reopening the pool required a <10% fresh water add. What could have caused the acid level to drop so dramatically over the winter?

Thanks,
BtBO

 

[jimcraig152]

Bacteria eats CYA and converts it to ammonia. Cheap aquarium test kit will show if you have ammonia in your pool. Other than that, splash out explains the rest of the loss. Simple fix is to add more of it.

 

[duraleigh]

Splashout and rainwater can usually account for most of the loss.

I would suggest calculating and adding enough to get to 20-30 ppm. You do not give your location (city and state, please) but that should put you no higher than 50 ppm total which is good for most regions.

Ammonia should not be a concern since you are holding some chlorine in the pool.

 

[Babe the Blue Ox]

Splashout and rainwater can usually account for most of the loss.

I would suggest calculating and adding enough to get to 20-30 ppm. You do not give your location (city and state, please) but that should put you no higher than 50 ppm total which is good for most regions.

Ammonia should not be a concern since you are holding some chlorine in the pool.

Thanks for the info. I'm in Tulsa, OK.

This is my 6th summer with this pool and I've never added any stabilizer since it was initially filled. I float some pucks for a couple of weeks while on vacation and that's always been enough to keep the CYA up to the 50 or so range through the summer.

That's why I was surprised this week as it's never been below 30 before.

 

[Scuba_Steve]

Thanks for the info. I'm in Tulsa, OK.

Please add this information to your profile.

It shouldn't just go away, but sometimes stuff just happens that we can't explain. Just get it back in there!

 

[kimkats]

Mine loses CYA over the winter as well. I really think mine is from the draining and refillingI have to do when it rains.

Kim

 

[Babe the Blue Ox]

Please add this information to your profile.

Done. How do I remove or update the signature. None of that info is mine.

Stabilizer is dissolving in the pool now.

 

[kimkats]

Here ya go!

Pool School - Getting Started

This shows how to fill in your info.

Kim