lol...just realized I posted the wrong thing......my ph down is what I use until my ph is in check (I think that is muratic acid...right??).....the CYA (stabalizer)......I haven't ever tested, but I just used the amount they recommend based on my size of pool...which was 2lb for aprox 10000 gal ( I think)......it seemed to work good for me and kept my cholorine in check. Maybe I should invest in a cya test kit though.