Plumbing a tank using bulkheads

[dpatte]

Hi

I'm looking for some advice on plumbing for a 210g tank I own.

Years ago I bought this 2nd hand tank that is drilled. It has two white bulkheads, over 2" in diameter, already on the right side about 2 inches below the waterline.

On the outside, what I would like to do is rig up a Mag 18 pond pump, drawing from one of the holes, and returning the water to the other, for a fastwater freshwater setup.

On the inside, I want to use plumbing to draw water from the far end of the tank to the bulkhead and pump, using buried plumbing.

The problem is that Im not sure what what standard the bulkheads are, or what standards of plumbing or fittings i should use for the connections. Im not averse to removing the bulkheads, and replacing them if that makes things easier, but I'm not even sure if I can removing the existing bulkheads to show someone without damaging them or the tank.

Who could share some advice?

[Dxpert]

Those bulkheads spin off, I would recommend replacing them with the rest of the plumbing you need to purchase, they won?t be too expensive to replace and the new ones will give you an easier time assembling. Bulkheads traditionally have slip glued fittings or threads. Sounds like yours have threads, depending on the setup you might want to use slip glued fittings. In short, replacing them will be easier once you get them off. The return is typically smaller than the drain. Are you putting a sump tank or just an external pump? If sump tank, I?d recommend two drains and another smaller hold drilled for the return