The minimum size would be just big enough to hold your proposed filtration (plus a little extra room for future upgrades).
As to maximum size...
The bigger you can make it, the slower water chemistry and temperature will change. A more stable water quality is always good, so I say build it as big as you have room for. I have a 300 gallon rubbermaid I use as a sump for my 135 FW community. It gives me plenty of room for filters. Also, the extra 200 gallons of water makes a great heat sink so I don't run the chiller too much.