I am trying to see what my FC consumption (loss) is in the daytime by taking readings at 8AM and then at 8 PM that evening. Yesterday I measured an 8AM FC of 8. My 8PM reading was 5 which is probably Ok. This AM the FC reading was 3 maybe 3.5 as I had to use 7 drops of R-0871 using the 10ML fill mark.. My CC readings have remained at 0.5. Is this OK or should I be worried that I may be seeing the start of an algae problem?
FC Testing
- Thread starter George Whitzel
- Start date
It totally depends on what your CYA level is. Maintain FC above the minimum. [FC/CYA][/FC/CYA] Heat, sun, bather load all effect chlorine daily loss.
My CYA is currently at 60. My testing is equivalent to an OCLT and I thought you fail if you lose more than 1FC overnight?
You lost me there! How is an 8 am to 8 pm an overnight chlorine loss test? the OCLT implies that sun is off the pool when started....and still off the pool before sunrise.
Last night at 8 PM the FC tested at 5. This morning at 8AM the FC reading was either 3 or 3.5 so this was an overnight FC drop of either 1.5 or 2.0.
Ps: the pool is clear and Cc is readings 0.5 or less.
Ps: the pool is clear and Cc is readings 0.5 or less.
FC levels are reduced for several reasons but from what I understand, one of the MOST SIGNIFICANT of these reasons is exposure to sun. So if you check your levels after sunset and then check your FC levels again before the sunrise the next morning, you can eliminate sun exposure as a possible suspect. If you lose much FC overnight, then something else must be causing it.
All of the usual suspects??
All of the usual suspects??
We get a lot of hot daily sun where I am out so a daytime drop of 4 FC does not surprise me. I have added some cyanuric acid to raise my CYA to 70 to see if I can reduce the daytime loss to 3FC. I can then run my SWG at 60% for 8 hours to offset this according to pool math.
You have something consuming your chlorine if you are losing that much overnight
I was not trying to run a OCTL test. I was actually only trying to determine my FC demand (loss) on a hot day so I could then use a table that someone on TFP sent me that calculates the duration and percentage that your SWG needs to run to maintain your target FC. I just run a FC test again and got a reading of 5.0 so there is no issue. I guess I must have done this AM test wrong. Sorry all.