I have used Amquel, Tetra's Aquasafe, API's tap water conditioner, and stress coat. Am I the only one who can't actually locate prime??? None of my LFS carry it nor does Walmart. First time I heard of it was on here. I'd like to try it at some point. A lot of the chemicals I have were given to me and were in date so I used them, the ones that were not I tossed because I just don't trust our water nor outdated chemicals. When those ran out, I purchased API's from my LFS and it seems to be alright, doesn't take much to treat my 30's. I have another bottle of something else it's grey but don't recall the brand name off the top of my head...it only takes a couple of drops to treat my 10 gallons. I have tap water conditioner all over the apartment, I guess because I have tanks in every room. And I also have a space in my kitchen (under the sink) dedicated to all my fish supplies because I don't have a nice fish tank stand/cabinet with space.