High CC in a covered pool.

Green Goblin

Gold Supporter
Nov 5, 2012
My pool is in Gainesville, FL.

We have a solar system that keeps the temp above 80F for 10 months of the year, so long as we use a solar cover.

This is my second season managing the pool with a cover. The cover is on most of the time, only opening it for an hour or so of use once or twice per week from about October 15 until April 15.

This weekend, I tested the pool water by simply reaching under the cover by hand to get a sample. I didn't fully open the pool, and we hadn't had the cover off for about 2 weeks, due to a recent wave of viral illness in the family.

On saturday, I got a questionable CC reading of 1.0 (using FAS-DPD). I can't remember the FC exactly, I think it was 5.5.

Because of the questionable reading, I retested on Sunday. FC=6.5, CC=1.5.

I was very surprised at the CC reading, and uncovered the pool fully. It looked okay.

I left the pool uncovered for 3-4 hours and re-tested FC=8, CC=0.5 (the CC test was just very barely pinkish, and 1 drop made it completely clear)

Is it possible that the CC reading was elevated due to being covered for a long time, and testing it while covered? Am I trapping that stuff in?

I'm not intentionally keeping my FC high-- I had to replace my SWG cell just about the time we covered the pool this season and I'm still trying to figure out it's performance. Presently it's on 15%.

Obviously I'll be retesting the CC values over the next week. Anything else to do, maybe an OCLT? Or do I just need to uncover the pool a little more often to let the CC out?


Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
Tucson, AZ
This sounds pretty normal for a covered pool. Usually a good idea to let the pool breath fairly regularly so that the CC can dissipate.

You could certainly raise the FC a bit and do the OCLT just to make sure there is nothing else going on.