iam not sure what size tank you have but if its over 4' i would say just get another one if you like, and they will take oposite sides of the tank, even if there a pair they wont stay in the same hole mabie just afew inches apart but aside from mateing they wont do much as a "pair",
and egg crate wont keep them in
off topic but did you get it at J&L? i was looking at the ones they had sure wish i could afford one
