Results from my New Test Kit


Active member
Jul 18, 2007
Thanks for all the help this summer. Pool is looking good. However I am getting frustrated with all the bleach I have been putting into the pool. I have been shocking for the last 3 years with ChlorBright per my local pool store. I wish I would have found your forum much sooner so my CYA was not so high. I have been following your charts and calculators but can't keep up with the FC.

Here is what I found with the TF-100 kit (Vinyl 22,000 gal):

FC: 1.0
CC: .5
pH: 7.2
TA: 115
CH: 200
CYA: 110 (pool store said 40)
Temp: 90 (Atlanta has been around 100 degrees for several weeks now)

Any suggestions to lower the CYA which I believe would help reduce the quantity of bleach that I have to add?


LifeTime Supporter
Apr 22, 2007
Your FC is low, so you need to shock at high levels, especially with that high of a CYA, in order to get rid of the CC's.

I would start dumping some water, you will need to dump about half to get into a good range. You can do it a little at a time, though and it should help as you lower it.

When you vacuum, vac to waste if you can.

Everything else looks pretty good.


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
Reducing CYA will nominally increase the amount of bleach you need. However in your case I suspect that you have something growing in your pool and lowering CYA will make it easier to kill it off and get back to more normal operation.

I don't recommend having CYA above 90 and somewhat lower than that is even better. You should reduce it by replacing water. The simplest way to do this is to add water continuously while draining water out to keep the water level more or less uniform. If you have an overflow drain all you need to do is add water, otherwise you will need to pump some water out while you add water.

With CYA around 90-110 you need to maintain FC above 8 and shock to 25 or more. Since you have unexplained chlorine loss it would be a good idea to shock right away. That means bringing FC up to 25 and holding it there until you have no chlorine loss overnight. This must be done agressively, testing and adding chlorine at least three times a day to maintain 25 or higher.

Once you shock the pool you should be able to hold FC around 8-10 with fairly little daily chlorine addition, perhaps 1 or 2 ppm per day.