Unable to get free chlorine to rise

[uncommongnome]

Pool is about 20k gallons.

I'm not having any luck getting free chlorine to raise. Currently it's so low that it's not even on the scale.

The prior owner used trichlor tablets and we kept using them when we bought the house last summer. I bought a Taylor test kit and saw that the cya levels were off the chartsl, around 200ppm. Rather than draining the pool partially I thought I would try the bioactive cya reducer. The levels were close to the ones below but free chlorine was around 1.5 or 2. After about 14 days of the bioactive the cya levels had went down barely, around 175ppm but the water started looking bad so I decided I needed to get it looking good again.

I also decided to stop using stabilized chlorine to try and slowly combat the cya level. Over the last 3 days I've used 1 gallon of 10% sodium hypochlorite liquid each day and 3lbs of cal hypo shock last night with no increase in free chlorine level as of this morning.



At 79 degrees this morning the levels are:

Ph 7.5
Total alkalinity 140
Calcium hardness 800 (very hard water where I am)
Free chlorine ?? Can't get any color change with the test, just mirky white.

Any suggestions?

 

[PoolStored]

Welcome to TFP!!!

Unfortunately, with CYA at 175, it is not possible to maintain enough FC to sanitize the pool.

You need to replace about 75% of the pool volume with new water. This will also correct your CH problem.

This should help you:

Draining - Further Reading

www.troublefreepool.com

 

[jimbethesda]

Pool is about 20k gallons.

I'm not having any luck getting free chlorine to raise. Currently it's so low that it's not even on the scale.

The prior owner used trichlor tablets and we kept using them when we bought the house last summer. I bought a Taylor test kit and saw that the cya levels were off the chartsl, around 200ppm. Rather than draining the pool partially I thought I would try the bioactive cya reducer. The levels were close to the ones below but free chlorine was around 1.5 or 2. After about 14 days of the bioactive the cya levels had went down barely, around 175ppm but the water started looking bad so I decided I needed to get it looking good again.

I also decided to stop using stabilized chlorine to try and slowly combat the cya level. Over the last 3 days I've used 1 gallon of 10% sodium hypochlorite liquid each day and 3lbs of cal hypo shock last night with no increase in free chlorine level as of this morning.



At 79 degrees this morning the levels are:

Ph 7.5
Total alkalinity 140
Calcium hardness 800 (very hard water where I am)
Free chlorine ?? Can't get any color change with the test, just mirky white.

Any suggestions?

Very hard water and you put cal hypo in there, making it worse. Unfortunately, the only solution is to drain 75% of it and refill. Then, only use liquid chlorine, or better yet, make your own chlorine with a salt chlorine generator.