I think melosu was referring to just the shrimp part of the question, because I think melosu was actually the person that suggested to me to lower my temp. when dealing with the snail issue.
But, as stated before, stability is the most important. Our tank is on the second floor with MHs for lighting & in order to keep our temp stable (& lower), we have to use two table-side fans on either side of the tank, blowing over the surface. In addition, VA weather doesnt help any. One day you need the AC
on full blast & the next you need the heat on