Originally Posted by LordErrorprone
The tanks would have to be the same size otherwise the bigger one would overfill the smaller one.
Size is not the problem, they have to be on the same level. Although too much difference would cause a problem.
I would use a sump, so when you had to drain the system the extra water in the tube would have some where to go. Depending on the system you could control the flow with a ball valve so the fish could swim against the current.
What would have happened if some one told the Wright brothers that their dream was a "pipe" dream?