I just joined this group as I have been trying for a couple of years to spawn my 5 - L46's ( I had six until a few months ago

I have decided to give them a more spacious abode as I thin a longer tank will do them good.
A couple of questions for setup
Ideal cave sizes? What size PVC tubes are best
How about filtration? I have contrived a PVC river tank style setup with foam sponges on one end of the tank and a submersible Hagen Aquaclear power head on the other end of the tank. But the powerhead I have is only about 7 times turnover per hour. If I lower the water level a little it will get up to ten times tank turnover per hour
Am I better off with 2 powerheads or just one?
How about height of the powerhead - should it be at the top of the water or blasting the pleco caves.
I have tried blasting the plecos before and they never came out of their caves. They did not seem to like the heavy flow rates at all.
This tank has a very thin layer of sand ( 2 cm) and larger polished rocks strew randomly around. I plan on some Java Fern on bog wood and Anubius plants for low light , high temp conditions