Thanks, I tiled the barrel to start with, just with a concrete cap
piece, it worked great, then I untilted it, and the water
falls/splashes too close to the edge for my liking; (more water loss)
and the top barrel sort of need to be more full ALL AROUND before water
would fall down. Or I would have to turn the pump so high it creates
"thick" waterfall and it end up hard to see the fishes.

I made a grate from mesh to avoid fish from falling into the lower
barrel, but do they do that? I think they probably would like to swim
against the current, not let the waterfall wash them down. But I put
the grate there to be sure.

Maybe you have a liner that the lip extends further, I find with tilted
I only get a small area of "dangerous" areas for fish on the top
barrel, where as untiled it is sort of high level all around..

Anyways, it really doesn't matter if I tilt it or not as I'm going to
make a fence anyway, the lexan sounds good, any plastic net would
probably soften when it is in the sun.