Well-known member
Apr 25, 2020
Oro Valley, AZ
Now with my CYA locked in and I understand the 7.5 % FC of CYA for my proper FC level , how often does someone need to do the 0870 test to get the exact FC ? Daily seems crazy as the test amount is pretty small. Using bleach with zero tabs so I am assuming my CYA should be stable - Is there a way to tell how often and what amount of bleach to use without doing this test every morning or night ?
thanks !

Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
Rancho Cucamonga, CA
Now that you've been tracking your FC daily, you should have a good idea of what your daily FC loss is (in ppms). It's probably in the range of 2-4 ppm. Use pool math to determine the amount of chlorine you need to add to make up for your daily loss. Keep in mind heavy bather load will lead to higher FC loss. You can probably get away with testing every couple days at first. If you're confident that you're adding enough chlorine each day, you can get way with 2-3 times per week.


Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
Franklin, NC
Yes, you will test daily for a while. As you see how your pool reacts to additions of liquid chlorine after a couple of weeks you may cut back to every other day for a while. Then you may do it a few times a week.

CYA tends to remain stable and testing may only be a few times a year.

Test pH every time you test chlorine.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
That K-1000 blue plastic box has the OTO chlorine test as well as the pH test. It is quite cheap, dependable and a good way to test chlorine daily.

So, use the OTO test daily to test for the PRESENCE (not exact amount) of chlorine. If your sample turns a shade of yellow you're good to go. Generally, it should stay the same intensity each day. If it tests clear or the yellow get's too deep, then switch to the FAS/DPD to get an exact result
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