Why not just get a BN, I have seen them do all the glass in a day, even the toughest spot algae, but for sure the younger BNs work harder.
Otos do a great job on diatoms.
Do make sure to feed them, when their work is done.
I think if I can fix the algae problem by properly fertilizing the tank that is a better option than adding a fish. I was considering ottos as an addition after the tank has aged a bit, so I was asking about there algae prefernces. thanks for all the input.