New Pool; New Water; How to add CYA


Platinum Supporter
LifeTime Supporter
Jun 28, 2009
For a freshly filled pool, how should I get the CYA to my goal level of, for example, 40? If I go to the calculator it says I need to add 16 ounces by weight of stabilizer to get to that level. Stabilizer in that context must be something specific because when I go to the "effects" part of the calculator it says adding 16 ounces of dichlor will raise CYA by 20. So, assume I need to add 32 ounces by weight of dichlor to get my CYA to 40. Adding 20 ounces of dichlor will raise my FC by 22, so I assume I need to do this in small increments to not put my FC through the roof. My question is:

When you guys talk about adding CYA, it always sounds like you add it all at once - ie, in a sock or dissolving it in a five gallon bucket. Is that because the CYA you are adding does not raise the FC like dichlor does?

I guess the real question for me is: I've been adding 1/4 cup of dichlor (which is about 1 ounce) daily to gradually build up CYA. I'd much prefer to get the CYA in there quicker and move right to daily bleach dosings. Am I right that I can't add my CYA all at once if I'm using dichlor, or am I needlessly dragging out this process? I may have just answered my own question -- if I go to the calculator again it shows that neither "stabilizer" nor "liquid stabilizer" adds FC along with the CYA. So, do I just go to a pool store and ask for "powdered stabilizer" and will they know to give me the right thing?

My second question is: a friend of mine had an AG installed yesterday and has probably filled it by late evening today. It is her first pool, so she's in the unfortunate position of coming to me for help. I'm no dummy - I sent her to you for help, but not sure if she's registered just yet. I gifted her a TFTest Kit and she took the bait and wants to do BBB! Yay! To get her up and running before her new water takes a turn and before she gets fully up to speed with postings etc, I'd like to extend my question about adding CYA for her pool. I intentionally kept this in my thread because it is the same basic question, but, she's big-league with a 24' round that is 52" deep. I think we figured her gallons at 14,400. What product should she use to add CYA and at what increment can she add it? I'm assuming dichlor is not the way to go for such a large pool. I can figure out the amount on the calculator and help her that way, but I'm sort of confused on what stabilizer to point her to -- ie, again, is that all I have to say to the pool store to get the right thing and then just introduce it via a sock or dissolving first in a bucket? Am I just looking for something where the only ingredient is Cyanuric Acid?

Thanks for helping out, as always!


Well-known member
Mar 18, 2008

This is a stand alone product that can be purchased at Wal-mart, pool stores, online, or where ever pool chemicals are sold. It is a powder that needs dissolved. You can dissolve in a nylon stocking or dump directly into the skimmer (don't back wash for a few days). There is a new product that is "liquid stabilizer" that dissolves quickly but it 2 - 3 x the price.

CYA is also found in the diclor and triclor pucks.

For simplicity....I use the stand alone products for CYA...and bleach for chlorine


Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
Houston, Texas
1. You can buy CYA without anything else added to it. It is also call conditioner or stabilizer. Look at the active ingredients listed on the label for at least 90% Cyuranic Acid. This is what we want hanging in the sock. When someone uses dichlor or trichlor you broadcast it on the water, since the chlorine would destroy the sock before it all dissolved. You can add 1/2 to 3/4 of what you need then test the CYA level a week later. This will help prevent you from overshooting your goal for CYA addition.
2. Doesn't matter the size of the pool. Look for something that is at least 90% CYA, put 1/2 to 3/4 of it in a sock and hang it over a return with the pump running until it is dissolved. Some people say squishing the sock after it is soaked in front of the return a couple of hours helps it to dissolve quicker. Use the pool calculator to find out how much CYA to buy.

You may want to check your local Walmart for HtH brand stabilizer before you hit the pool store. It will be less expensive and several folks here have been happy with it.


LifeTime Supporter
Jan 11, 2009
Cupertino, CA
crek31, you have a very small pool (3300 gallons) and to use pure CYA you would need less than 1lb. CYA typically comes in 4-5lb containers so buying pure CYA means you would have to buy enough to last several years. That's why the seasonal/temporary pool guide recommends using dichlor to build up CYA (in your case, 1.5 to 2 lb). It works perfectly well and should take maybe 10 days to 2 weeks.

You can use pure CYA in a small pool, just be aware that you will have no choice but to buy more than you need up front.

Your friend, on the other hand, has a much larger pool (14,400) and so for her it is more reasonable to use pure CYA.


Platinum Supporter
LifeTime Supporter
Jun 28, 2009
Thanks ideliver, zea and paul. I do know the dichlor works, I just think adding bleach is easier, so maybe i'll go in on some cya with my friend and between us get it used.

I saw some that said 90 percent CYA and 10 percent "Other." asked pool store guy what the other was and he didn't know. I asked if it could be copper and he said he didn't think so but he wasn't sure.

Do I need to worry about the ten percent, or is this the "pure" CYA my friend needs and I want?

Thanks again!

Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2009
SouthWest Alabama
We've seen several concentrations of cyanuric acid listed here and always recommend greater than 94%. It's easy to find even at 100% (the Wally-World brand is 100%). Not knowing what the other 10% is is a big deal to me. It may be something completely innocuous but then again it may not.


Platinum Supporter
LifeTime Supporter
Jun 28, 2009
Okay, thanks. I'm off to Wally World in the am to get this sped up a bit. I appreciate the assistance!


Well-known member
Jul 20, 2009
S. California
I was advised and successfully used ChlorBrite from Leslie's Pool Supply. They sell 1 pound bags. I dissolved half a pound in a bucket and added each night. I quickly got my CYA to 40. I just did it again two weeks ago when i opened the pool. Good luck!


New member
Jul 6, 2015
what is the best way to put CYA in a 10' round, above ground vinyl pool, I was looking at other pool sites and they said not to broadcast it, I'm confused on
what to do. Help.


TFP Guide
Jun 5, 2012
Central PA
They recommend putting it in a sock, securing it, and hanging near the return. Squeezing it periodically helps it along quicker.


Well-known member
May 30, 2012
Montville NJ
I use a cotton sock (like a athletic sock). I can hangit in the return and with about 10 minutes of continuous squeezing I can get a sock full of CYA into my pool.

I do get a few granules on the bottom, but nothing crazy.