What's the point of the MP20 in the 110, just random flow or do you want to get a wave? I would imagine a wave with the MP20 would be difficult in that size of tank. Reefcrest might work out pretty well however if the dart is supplying the primary flow. I have a MP20 in my 58 and I really could use about another 10% power.
If in doubt and you have the spare cash, jump up to the MP40. It's very easy to adjust the amount of flow.