Using the Bleach Calculator found here: http://home.earthlink.net/~mwsmith70...achCalc262.exe

You can click on "More Calcs" at the top left and you'll see a calculator for CYA. It tells me that for a 23000 gal pool with NO CYA you'll need 11 pounds to get it to 60.

But the only problem here is you really need to know for sure what your CYA is NOW!! I would guess it's zero but I would test it to be sure.

I would download the program and play around with it. MWSmith2 here at the forum made the program and here is a link to a thread which discusses it: http://www.poolforum.com/pf2/showthread.php?t=1637

Hope this helps.

Russell