Do you know what size the joist are, if the tank can run perpendicular to them or is it going to run parallel and is it going to sit against a bearing wall or not? These are all factors in deciding how big you can go.
Depends on few things. Where you going to put it ? Your going to get all different answers. I won't go bigger than 75 gallon. Especially if you add sump a other 20 gallons.
Its not going on a bearing wall and not sure which way the joist are running its going next to my desk. So if a 75 gallon will be fine than ill jus got with that... Was looking to put a shark tank but i guess thats out