Chlorine Level Stays High

[Rhumbline]

Hi All,

I switched to a Salt System (Mineral Springs) about 2.5 months ago. At the same time I found this forum and I am going through the learning curve. After getting a K-2006 kit I have found that my Chlorine level running at 11ppm - 13ppm at the 80% setting my dealer told me to set the salt gen at. We have gotten the level down and I am working on getting the perfect setting still, but it seem that about 23% will be right for this 20K gal pool.

I am shocking the pool monthly using 6% bleach and I am not having any sort of problems with the pool other then calcium deposits which are due to high calcium. We have never had algae problems at all. So my question is this, when I shock the pool to 10 PPM, it takes many days (3-5) for the level to come back down below 3 ppm. I have to turn off the chlorine generation or it takes even longer.

I suspect this may be due to high CYA which I know I have. This was caused by the previously used stableized pucks that were used in the pool. We are slowly getting the level down, but doing one large water drain & refill will not be possible due to the high price of water here in the Texas desert. Here are where my levels are running....

FC=2.5 - 3.0 generally

CC=0 (rarely do I ever see even 0.2 ppm even with heavy bather loads)

PH= 7.2 - 7.8 (this is my weekly flucuation with one gal of m acid to lower from 7.8 - 7.2)

TA=120 (fairly stable)

CH=400 (again we are trying to lower this as we replace water)

CYA= 130-150 (we measure w/ K-2006, so over 100 is just an esimate. It's slowly coming down though)

Salt=3100

TDS=3400

So overall I'm happy since the pool is crystal clear. My only concern is that when the pool is running over 3.0 to 10.0 ppm chlorine I am concerned about guests swimming in this high level of chlorine. And I don't really want to shut down the pool for 5 days a month to wait for the shock to burn off.

[waterbear]

You are correct that the high CYA is causing the chlorine levels to stay high. However with your high CYA levels you need to be running a higher FC to have properly sanitized water since much of the chlorine in your pool is actually in the form of chorinated isocyanurates and not in the form of hypochlorous acid. I would work on getting your CYA down to the recommended 60-80 ppm level as quickly as possible for a few reasons. Until you do you shold run the FC at about 6 ppm and you do not need to shock unless you test CC over .5 ppm.

With your high CYA your water is actually swimmable up to about 12 ppm FC and if you do need to shock you need to bring the FC up to about 25 ppm.

[Rhumbline]

Thanks again Waterbear! Your answers are always very helpful.