1. How many Tangs could I put in a 180g?
Not sure sorry
2. Do I have to have a sump if I want a reef?
I think any tank over 40 gallons needs a sump
3. What is your tank size that you may upgrade to one day?
I plan on having a 250
SW tank one day that will be a walk around in my entery way or living room.
4. This will certainly be my last upgrade, so do you think this is too small?
YES, but then again I dream of an 250gallon tank at least once a week. I just love the foot print of a tank that large.
5. What is the highest number of gallons tank you would upgrade to before you thought it was too much work?
Id think anything over 300 gallons would be to much work.