Questions regarding BioCube 29g

[edikpok]

I've had this baby for a while and recently I've been having some problems with my stock pump. It pushes out all the water out of its own compartment, but does not get refilled from the adjacent compartment. So it basically blows out air! Has anyone encountered such a problem before? The pump itself works....is there a way to regulate it?

Would you guys recommend putting a cowfish or a dogface puffer or a dwarf lionfish in a 29g cube?

On an unrelated topic - is it bad if you have your tank standing close to a speaker? (not subwoofer!)

Thanks!