It's way undersized for a 90 gallon, 1" drain. You'll want the Eheim 1260 at least, preferably the 1262. There's a lot of head pressure to return water from the sump to tank.
For refugiums, about 2-3X turnover is plenty. Some people like a little more, but you don't need much flow through a refugium. If it's a 30g refugium, I'd say 50-100gph is plenty.
