Very high FC with 0% CC


LifeTime Supporter
Jun 24, 2009
I'm somewhat confused this year. Last year was my first year with the pool (35,000 gal freeform vinyl). I check the levels every other day. The water was always perfect. Last years levels were:

FC - 5 to 6
CC - 0
PH 7.4 to 7.6
TA 100-110
CH - 40
CYA - 40
Salt - 3200
Salt cell set at 65%
Pump operates 8 hrs at HS and 16 hrs a LS

This year the pool was shocked on opening by the pool builder. However my FC is really high in the past two weeks it has gone from 8.5 to 15. The CC is still zero

My level today is

FC - 14
CC - 0
PH - 7.4
TA - 80
CH - 50
CYA - 50
Salt 3400
Pump operates 8 hrs at HS and 16 hrs at LS

Yesterday I reduced the salt cell to 45% and the FC droped from 15 to 14. Due to the the colder weather (high 60's to mid 70's) no one has been in the pool for the past week or so.

Today I shut the salt cell down. (Super Chlorinate is turned "off"). I use Taylor K-2006.

Any ideas?

Thanks in advance


LifeTime Supporter
Jun 24, 2009
Richard, Thanks for the reply. The water is crystal clear. I was just concerned with the really high FC numbers compared to last year when the cell was set at 65%.


LifeTime Supporter
Jul 17, 2007
Rockville, CA
You have already identified the possible reason for the difference in FC levels observed from one season to the next. A reduction in bather load will place less demand on FC. You also have a slightly higher CYA level this year that is reducing loss of chlorine to the sun. I would be willing to bet that if you brought your CYA level up to the minimum suggested by the manufacturer, you would reduce chlorine demand even further and could dial down the SWG a bit more. Just a thought.