I'm looking for some ideas or things that you guys have looked back on a went "Ohh man I wish I would have done that!!"
One thing that I am thinking about is putting a power head near the center of the tank but need some ideas on how to hide the wire coming down the back of the tank inside. I'm already doing a rock wall but do I want to put it behind the rock wall (the wire) and then what happens if I need to remove the power head...? Yeah not a good idea.
I have done this 2 different ways and had issues with both. I have had them move, clog and break. Keep the pumps together and as high up in the rocks as you can. Use tubing, hidden in the rocks to get the flow were you need it.
Few things that I wished I did when I started the hobby.
1. Larger sump 2. Back up equipment 3. Fail safe plumbing ( Incase water reverse siphons) 4. Efficient yet powerful main pump to reduce the power heads in the tank 5. Frag system to allow for taking personal care of my corals if they get stung or stressed 6. QT for fish and QT for corals ( Cant emphasize enough) . 7. Label each cable
My main regret is not having the tank drilled for an overflow... Hang-on overflows suck!
As for your wire hiding... what about using the same material you build the wall with to coat the cord of the powerhead. Then it would blend in and still be accessible. You could even build the wall in such a way that the cord(s) tucked/locked into the wall structure.