Best way to add large amounts of CYA to new pool


Active member
Aug 22, 2015
Columbia, SC
While 26 is a touch low, it is better to be a little low than high.

Your method to raise it with TriChlor is very good being 30 is a good place to be and you are already close I wouldn’t add CYA. Even if you overshoot to 40 or 50, you are still in the zone. 40 is probably the best place to be... Once reached, I would personally strive to sodium hypochlorite and maintain.

If your pool is algae-free with clear water and no combined chlorine, then I would keep my chlorine at 4 ppm minimum and really not worry about borates or phosphates being algae cannot live in your water if the chlorine level is at least 4 ppm provided your Ph is also in range. If your a CYA climbs to around 35 bump up to 5 ppm free chlorine... At 40 ppm, I would stop adding TriChlor and make the switch though to Sodium Hypoclorite.

It wouldn’t be worth lowering the phosphates at this point as that is just added expense. If you want to increase the borates for slick feel and they are not already high, you certainly can, but it will also raises your Ph.

What I am saying is if Ph is low and borates are low, adding borax is a great remedy, but if your pool is already climbing on the Ph scale, I would not add any Borax. It would be good to have a jug of muriatic acid on hand to lower the Ph if it gets any higher than 7.6


Well-known member
Aug 18, 2018
Dieppe New Brunswick
40oz of Trichlor should raise CYA 6.6. I understand that CYA should be between 30 and 50 for a non SWG pool. I also understand that there is a relationship between CYA and FC levels.

Back to the original poster. The powder sounds interesting. I would use 2 pails. Dilute to a slurry in 1 pail and then
take some slurry and further dilute with pool water in the second pail. Slowly pour the second pail in front of a return watching for any heavy sediment at the bottom of the pail. If there is stop and add more pool water. Repeat as often as needed.
This would be almost as fast as liquid CYA but cost less.

The CYA sticks I used took too long to dissolve especially in cold water. It does however add CYA.

The sock works, but don't add CYA directly to the skimmer. If you rinse off a clogged filter [clogged with CYA], say goodbye to your CYA.

The Tricolour is pushing PH down a bit. Borox pushes it back up. My phosphates were 4000 last year and I opened a green pool. It cost me $40 to bring the Phosphate level down. This year I opened a clear pool and the phosphates are 282. At this point I won't worry about phosphates.
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Gold Supporter
Aug 31, 2015
Harrison, NY
Netwizz, I bought brand new reagents from the TFP store. I was leery that my CYA was so low on opening, but the new reagents and the old both told the same story.


Gold Supporter
Bronze Supporter
Jun 29, 2016
Tampa, FL
I would also make sure your reagents are not expired for testing CYA because unless a lot of water was replaced from closing to opening this year perhaps the reagent is not making it cloudy enough to properly register all of it. CYA doesn’t disappear.
Oddly, every fall I have CYA at about 70, and every spring it has dropped to near zero.


Gold Supporter
Bronze Supporter
Jun 29, 2016
Tampa, FL
By the way, I once invested in liquid CYA. Used some of it, stored the rest. When I went to use it again a few months later, I had a solid block of CYA floating in water. ?

I used it just like we use the dry - broke it into chunks, put it in a sock, and hung it in the pool!