CYA levels


New member
Jun 15, 2012
I just found this site prior to putting my first pool in. So awesome finding all this info. The pool is a 24' abg and 48" deep so roughly I figured 13000 gallons. I placed 4 lbs of CYA into a sock and let it dissolve into the pool in front of my return 6 days ago. I have tested yesterday for CYA and the test only read 20. I know that I was like 4 oz short of CYA to have a reading of 40 but wouldn't it have shown up closer to full reading by now? My daily fc loss is between 3-4 everyday due to the pool getting anywhere from 12-14 hrs of sunlight directly. I had placed in 2 7oz trichlor pucks to add just a little bit of CYA at a time (don't plan on using them in the future, but since I had them thought what the heck).

I'm at work but I'm pretty sure my numbers are as follows:

FC: is normally 4 when I check every night ( I raise to 7 after testing)
CC: 0
PH: 7.5
TA: 100
CH: Never checked since vinyl pool
CYA: only reads 20

So should I wait and just see if I CYA goes up in the next few days or should I make a trip in and buy more stabilizer? We are having our first pool party tomorrow night so I am planning to dose heavy tonight on the bleach and then again on Sunday when I get up in the morning. Anything else I need to look at doing in regards to the pool chemistry? It looks awesome right now all sparkling and clear, but don't want to mess anything up.


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
Welcome to TFP!

You should get more stabilizer, wait till it has been a full week, test the CYA level again, and adjust from there.

64 oz would raise CYA to around 35, which is on the low end of the range. Even if it gets up to 35, you should still add a little more.


Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
Tucson, AZ
:wave: Welcome :wave:

Using your estimates ... the CYA should get up to about 37ppm.

How are you doing the test? The lighting can have a major affect on the reading. Review this:

Might want to give it a few more days and redo the test.

Sounds like you have a pretty good grasp of the chemistry (you should check the CH as you can still suffer scaling if it gets too high and you let the pH drift up).

Just bump up the FC (keep below shock level ... say below 10ppm for now since your CYA is a little iffy) for your party and you are good to go.