You absolutely can use bleach in a vinyl pool!! Pool store "liquid chlorine" is 12% sodium hypochlorite. Plain, generic ultra bleach is 6% sodium hypochlorite. Same stuff, just a lower concentration. Haven't met a pool store person yet that can tell me why it's okay to put 12% bleach in a vinyl pool, but not 6%!!! My pool is IG vinyl liner, and bleach is basically the only chlorine source it ever sees, so I can tell you from experience that it's okay.

Anyway, in a 30K gallon pool, each 2.5 gallons of 6% bleach will raise your chlorine by 5 ppm. And when Watermom said 15 ppm, she meant 15, no decimal points! After you get to the initial 15 ppm, then each 1/2 gallon you add will raise your chlorine by 1 ppm, so you can use that as a guide if you find that you're losing chlorine overnight and need to maintain that shock level a little longer.

Janet