Only thing I have currently is bulkhead in the tank. I have some hard line and was gona use some of that flexible pound line maybe, so a combo of both. Not sure yet. Any help from you is welcome! =)
Let's start with some pics of what you are working with. Anything with a bulkhead or usable hole (including towers) although if I recall you said you didn't have overflow towers, correct?
The main objective is to make sure you place the inlets to your pump (suction from inside the tank low enough that you will have enough water volume to properly backwash.