Question about CYA Level


Active member
May 21, 2012
Kansas City, MO
So I've been testing my pool levels daily using the TF-100 and my CYA is pretty low. Reading the following from pool school, does the "sock" refer to just an old sock, or would this be something like a skimmer sock? I don't presently have a skimmer sock, but hope to get one. Also, once you put that in, is it okay to swim during the week that you're waiting for it to come up, or even right after you add it in?

I have some trichlor tablets that I'd like to be able to use considering I spent the money on it earlier this summer. Is it best to avoid that since I'm using the BBB method now, or can I still put those in my floater. Am I correct that this can raise CYA levels a little bit? It looks like I need about 34 oz of stabilizer to get it to 30, but I only have a bottle with 1.75 lbs right now. (sigh)

"Solid cyanuric acid should be placed in a sock, and the sock put in the skimmer basket. After adding solid cyanuric acid you should leave the pump running for 24 hours and not backwash/clean the filter for a week. Solid cyanuric acid can take up to a week to fully register on the test, so it is best not to test the CYA level until one week after adding some."

My readings are as follows as of checking last night. My water looks great and is clear. I know the range for a vinyl pool is 30-50, but is there a particular level I should be aiming for? I was holding steady at 30 for some time before, never above that.

FC = 3.5
TC - 0
TA = 90
CYA = 20
pH = 7.4 (added some borax last night to bring it up to 7.5)

Thanks very much for your assistance! I'm real happy with how things are going using this method!


LifeTime Supporter
TFP Expert
Jan 6, 2010
San Dimas, CA (LA County)
Yes, just any old sock will do. One without holes. I'd use one that has lost its mate. :mrgreen:

Yes, you can use your trichlor pucks to add CYA, too. Down near the bottom of the Pool Calculator, it will tell you the effects of adding however much trichlor by weight. Be sure you have entered your pool volume. A 3' puck weighs 7 or 8 oz, depending on manufacturer. Aim low, you can always add more.