How much cya in a puck?

[mepot101]

I'm full of questions today.
After my drain and fill to lower my cya from ~150, it ended up about 35. ( I know, call it 30 or 40).
Now we have had a BUNCH of rain, so my cya is right at 30. I guess that's ok, but if I need to add a little cya, how much will each puck add? I have a lifetime supply left from my constant puck days.

Also, will they go bad? I suppose even if the chlorine in them gets weak, the cya will be constant?

 

[ajw22]

8 oz of trichlor will raise your FC by 3.4, raise CYA by 2.1 and lower pH by 0.18.

We round CYA up so you call 35, 40.

 

[YippeeSkippy]

Just to be clear- in *your* size pool its 3.4 FC and 2.1 CYA as Allen says, but its pool size specific.

In my smaller pool 8 ounce puck of trichlor would give me 4.8 FC and 2.9 CYA (and dip that pH obvioiusly).

You can always pull up PoolMath (either the App or the classic web version found below) to check on the effects of adding chemicals. Just make sure you input your pool size first though.

Pucks should last a long time if kept well covered and dry.

Maddie