CYA - Define “disappear” please


Well-known member
Mar 26, 2014
San Jose, CA
The CYA test should really be done in bright sunlight with your back to the sun and the tester at your waist in the shadow of your body. I like to pour the solution to each line, look away and look back. If I see the dot, I pour to the next line, and so forth until I come to the line that I don't see the dot when I look back. Try not to stare at the dot for too long. Your mind will play tricks on you. Look away, look back.


Bronze Supporter
Mar 5, 2020
Melbourne, Australia
Pool Size
Salt Water Generator
SWG Type
Astral VX 7T
I’m going to hold off on adding calcium chloride and see how the cal-hypo changes things over the next week or so.

With each ppm of chlorine you add to the pool with cal-hypo, you will also increase your CH by about 0.7ppm. Do, if you for example have to add about 4ppm worth of cal-hypo per day, then this will increase CH by about 2.8ppm. After a month that would add up to nearly 100ppm. If you only need 2ppm of chlorine per day, then it'll be about 50ppm of CH on a month. Just to give you a tough idea.

Low calcium is only really critical for plaster pools, for FG pools see Texas Splash's advice above.

What is critical for all pools is high CH, which will lead to ugly scaling. The water parameter that shows if scaling is an issue, is the CSI. You will also have to measure the water temperature and enter that into PoolMath, then it will calculate CSI for you. You don't want CSI above 0.3. With constant usage of cal-hypo you would eventually get there.


Gold Supporter
Hi Jess.
Here is some info on the CYA test in case you missed it, in particular the temp thang:

I like Dean's procedure for testing CYA.. just fill to each line. There is no reason to try and interpolate between them. And in fact its nice to read through all the things that can cause water testing errors. And then just keep that info in the back of your mind:

You are doing great! carry on!
Last edited:
  • Like
Reactions: JessM and HermanTX


Bronze Supporter
Apr 27, 2020
Clarksville TN
Pool Size
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-9)
Great advice, I’m going to try the fill to the line trick for the CYA test next time. My new fiberglass pool was installed last November and i’ve gotten the hang of the testing with this site. I did slowly raise my CH to 200 and the dirty waterline has really decreased in appearing so often. I wipe it with a cloth and a magic eraser every so often, and it stays sparkling for a long time. My Warrior SE is great too, can’t imagine trying to keep the pool clean without it. The skimmer socks from Lowe’s have been great too, I just tried those recently.


Silver Supporter
Jul 31, 2015
Southeastern Oklahoma
JessM, I have the same problem with my rural water in Southeastern Oklahoma. The water comes from Lake Eufuala (muddy) then goes to get cleaned up. Ha! Many times, I have turned the kitchen faucet on and brown water came out. Difficult to keep the pool chemicals in check.
  • Like
Reactions: JessM
Thread Status
Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.