get a 405 or another 305 too
the u series filters dont produce a strong current but are really good filters i use 2 u3 in a breeding tank plus a wavemaker
i dont see and issue with the zebra you already have just avoid keeping the fry!
the frebergi is a hap and wont do too well with mbuna
a great blue fish which sit hi in the tankwouldbe acei
you should look into afras mate hara chiwindi mbamba lion sanga all real nice fish
ukcool are you in the us or uk?