Ok i have a 75 gallon african cichlid tank with a fluval 305 and an AC110...I was given a rena XP3.....I want one HOB and one canister so should I keep the 305 and get rid of the xp3 or ditch the 305 and use the xp3? the xp3 is for up to 170 gallons and the fluval is only 70 but they are close in price...what gives?