This may help to know:
I have been told, by David Hodges - Inventor and manufacturer of Quick-Clean, that Chalk-Off is a blatant rip-off of his product. He told me the product formula was changed, it does not work as well, and is potentially dangerous to your health with repeated exposure (such as playing pool daily)
I have even seen commercials (which may be old and out of circulation) that show David Hodges using the product and then an image of Chalk-Off pops up. The product David was using in the commercial was actually Quick-Clean, as it was actually a Quick-Clean commercial that was ripped off and edited to look like a Chalk-Off commercial. I know this is hard to believe, but I know David personally (I designed the Quick-Clean can label) and I have seen the commercial with David in it. If I remember correctly, the label/logo for Chalk-Off may have even been a rip-off of his label - with his personal photo still on it! (not sure about this though, its been a while)
I believe at one point David had a lawsuit in the works against the manufacturer of Chalk-Off, but I don't know the current status. I haven't spoke to David in a while, but I know those types of cases take a while...
Anyway, my suggestion would be to switch to Quick-Clean.
David's website is
www.quick-clean.com (I think, if not, google it)
Personally, I don't know much more than what I have explained, I just thought this might help.