Zero CYA

[crispyjim]

Howdy. Great place for great information (still - see postscript)
I'll try to keep this as simple as I can.
My tests this AM gave me the following (Taylor K2006).
pH 7.8
FC 4.4
CC 0.2
CYA 0 (at least, no reading)
TA 290

I've added 3 cups of muriatic acid about 3 hours ago.

I'm wondering about the CYA. I have 25 lbs of 100% CYA but wonder if and how much I should add.
Also, when should I check the pH again?

The pool is clear with no sign of algae.

Thanks for any and all help.

P.S. even though I just joined yesterday, I'm unable to post in the getting started area. Not that it matters, but I was a member many years ago. I don't recall the username I used.

[AnnaK]

The container of CYA will have dosing instructions on it. You're looking for 30 - 50 ppm, so calculate the amount you need for your pool volume from the instructions.

From your test results I gather you're using a 25 ml water sample. You don't need that much. You can use 10 ml, one heaping dipper of DPD powder, then count the drops until the solution goes clear and multiply by 0.5. The resulting number is your FF and, subsequently, your CC value.

What is your goal with the addition of muriatic acid? Are you trying to lower your TA or your pH? This link http://www.poolforum.com/pf2/showthread.php?13111 may be helpful.

[crispyjim]

Thanks for getting back to me so quickly.
I'm trying to lower the pH with the acid. It seems a bit high.
You're right of course. I'll check the CYA container.
Again, thanks for the help.

I'm a little confused by my lack of CYA since I use a feeder with trichlor (it should be adding CYA, no?) along with 6% bleach. I've been going through quite a bit of bleach lately.

[AnnaK]

The trichlor pucks add from 6 - 9 ppm CYA for every 10 ppm of chlorine. It's a slow process when you start from zero at the beginning of the season.

You can use dichlor powder which is stabilized chlorine (similar to trichlor but in powder/granular form). The problem with dichlor is that it may contain other stuff that we don't want. So can the trichlor pucks. The other day I saw some that contained 1% copper. We definitely don't want copper. If you have access to a Sam's Club, their Kem-Tek dichlor "shock" is good. You would put that in the pool according to label directions so you'd maintain 5 or 6 ppm FC. I do not know how much CYA dichlor adds, I bet the mods have that info handy though. Use dichlor until the CYA level is around 40 ppm (+ or - 10 ppm) and then switch to just bleach.

What do you mean you've been going through "quite a bit" of bleach? How much is that on a daily basis? How does your pool bottom and sides feel? Slick? Or squeaky clean?

Until you have enough CYA in the water the sun will break down the chlorine very quickly.

[BigDave]

Dichlor adds 9ppm CYA for every 10ppm FC. It also disolves very quickly unlike pure CYA.

[aylad]

If you used trichlor last season, and had zero CYA on opening this year, you might be experiencing the ammonia demand that we're seeing a lot of this year--happens sometimes when the CYA breaks down over the winter. Try testing for chlorine at night, and then test again in the morning before the sun hits the pool. If you have more than a 1 ppm loss in that time, then you have something in the water that the chlorine is battling, and you need to raise it to shock level and hold it there until whatever is there is gone. If it's ammonia, it can take LOTS of chlorine, but it needs to be done.