New member
Jul 9, 2010
Lets say I have a accurately measured CC of .4 at a FCL of 4.
Lets say I shock (with 6% bleach) at the proper ppm level considering all the other pool water parameters

How long should it take for FCL & TCL to equal each other with noone using the outside vynal pool & when & if FCL & TCL equalize, should it be at or around FCL 4 ?

Thanks Ed


LifeTime Supporter
Apr 27, 2010
Fleming Island, FL
Blivit, welcome to TFP

The CC reading you show of .4 is not necessarily a bad thing. If for instance you do an over night FC test perOvernight FC Test, and you get a reading of 0.5 ppm or less CC, you lose 1 ppm FC or less, and your water is clear, you do not have to shock. I see you are worried about the level of FC returning to 4 and equilizing with the Total Chlorine (TCL). Equal TCL and FCL is not completly necessary and could be a little different. Can you post all the readings and tell us a little more about your pool so we can help you out further?


TFP Expert
LifeTime Supporter
Nov 5, 2008
CC could go from 0.4 to 0 in a day or several. If no organics are being killed meanwhile, the sun can probably get that to 0 in one day.

Now FC = 4.0, CC = 0.4 (theoretically since our test kit measures either 0.5 or 0.0), and therefore TC is 4.4 since TC = FC + CC

When CC goes to 0, FC = 4.0 and TC = 4.0. Except that the sun will have burned off some FC and so it will have declined during the daylight hours.


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
CC comes in many different forms. Some break down very quickly, others quite slowly. There is no specific amount of chlorine, or amount of time, that is required to remove the CC, all of that will vary depending on just which compounds in the CC family you actually have in the water.

Generally, higher FC levels and more direct sunlight on the water will break down CC more quickly.


New member
Jul 9, 2010
Thanks for all the replies. I think my situation is ok now that I see that a CC level of .4 is nothing to get alarmed about. I misunderstood the "alarm point" for CC level. I thought that if one had an CC level of .3 one should shock etc etc. My 24' round 4ft deep vynal pool is fed by "well water" so
I thought I may have big trouble with impurities in the water. I must say though that my water is crystal clear & has no smell to it. I've had this pool for years but b4 now, have only used "pool test strips" to test the water. With test strips, CC is unknown.

I shocked my pool a week ago at 20ppm using 6% bleach 540oz (13000gal) cya = 6.8 ph 7.5
My CC was around .4 at shock time & after about a week the FCL = 2.27 & TCL 2.44 = CC of .17

So I think I will now bring my FCL back up to 6 & not worry about the CC till I see something .5 & above. I use the ColorQ Pro 7 tester & I have seen the pro & con comments about the unit.
My neighbor has the same size pool as I have & is also fed with well water (although his is a deepwell whereas mine is a shallow well) His FCL & TCL both read 6.68 :cry:

Like I said b4, my water is beauitful & wet & don't stink, so I'll keep an eye on things.

Thanks to all
Glen Allen, Va.