I use Tropic Marin, not the Pro Reef. The Pro Reef actually has less calcium and alkalinity. Tropic Marin is one of if not the best salt out there. It is all pharmaceutical grade ingredients so it is extremely uniform and high quality.
all of the canned salts settle during shipping, so none of them are consistent. only the salt mixes with separated components will be accurate.
that said, i use various reef grade salts, and they all work fine. take your pick.