Plugging the Holes??
 

I have a 240 gallon tank that has dual overflows in the rear corners (bottom pane).

For the time being, I do not plan to use the overflows and sump and I plan to remove the overflows to maximize tank space.

I know that I could patch over the holes (2" I believe) with glass, but I want to use them in the future.

Would threaded pipe plugs in the bulkheads work? Would they sufficiently withstand the water pressure?

Any advice is greatly appreciated.

That is the way that I would do it. Install the bulkheads (make sure they have inside threads) and then thread a plug into each bulkhead. Make sure you use Teflon tape on any threaded fittings whenever you are plumbing with PVC.

make sure you use a threaded plug inside the tank that way later on you can complete your plumbing under the tank befor you have to remove the plug

probably already thought of that though

Great. Thanks for the replies.