hi i have a 150 gallon.. and one rena xp3 . im going with fresh water .not sure off what kind off fish but i plan to put as much off a variety as my tank will accept .now ive heard that one xp3 is all i need .. then ive heard that i need at least one more . im new to this and want to set this up in the best way so that i have the least amount off maintence .i know they are alot off work . do i need another filter or something else .. help. i need education