Thanks for a great description!
A couple of questions:
A bulkhead fitting should have a rubber gasket that will seal properly without additional sealant
Since bulkhead fittings were suggested, I've been looking them up. The installation seems easy enough, but in all the videos I see I am stuck with a hole with threads on the outside, no one shows what comes next. What are the parts I would need for this? Do I need a join to connect the threads on the outside of each container?
The sides of the container won’t be parallel to the ground, so a straight pipe will put strain on the container that will lead to a failure. You will probably want to use flexible hose to connect the two containers, but two 45 degree elbows at each end of ridgid pipe(so 4 total) can take the strain out once you play with the orientations.
I didn't really understand this. Do you mean there will be strain due to the downward force exerted by the weight of the pipe and water? I'm hoping to have the distance between the tanks as short as possible, and the diameter should also not be too big.
Ah, I've seen those kinds before, and that seems fairly simple. Thanks!
Of course, now I understand what you meant! Yes, the boxes are slightly tapered, so that would be an issue.
Great tips, noted! Now I'll have to figure out where I can buy these locally.
Thanks again for great help!