[76Red18]

1. I put one about 2" from the bottom with an elbow to create a circular flow and one 1" from the top(above water level) with a slit to create a fan shaped spray for aireation. The one on the bottom is the one that will drain the tank if my pump shuts off.
2.I put mine 3" below the top and it could be lower. some water comes out on take off. I ended up makeing a seal with weather striping and a little latch to keep it shut tight.
3. As long as theres an inlet below the water level theres no way I could figure out how to stop it. It will drain down to that level. IMO an inlet close to the bottom is necessary to prevent bait from settleing on the bottom and dying.
4. I'll post a pic of the ones I made. Its a pvc threaded cap with a slit cut into it.
5.Plumbers putty

IMO 1100 gph minimum for that much water