cutoff bulkhead and use male threads??

[100_corner_pent]

I am fairly certain that for example, I have a 1/2" bulkhead fitting.

the inside diameter of the female threads is of course 1/2", and it fits 1/2" male pipe threads.

The outside of the bulkhead fitting is also threaded, so the retaining nut can thread onto it.

The end of the bulkhead has no threads right at the tip, so the retaining nut is the only thing that really screws onto the outside of the bulkhead fitting.

however, I also tried this retaining nut on the mpt threads of a 3/4 inch male piece of threaded pvc..and it fits.

So, i figure, you can get more flow through a 1/2" bulkhead fitting rather than using 1/2" pipe inside the bulkhead, use 3/4" female pipe on the outside of the bulkhead fitting, but first you should screw the retaining nut on all the way, and then cut the end of the bulkhead to remove the part that is not threaded at the end, and then unscrew the retaining nut slowly to clean the newly cutoff threads. then, any 3/4" fitting should fit over the 1/2" bulkhead and give you more flow.

I am trying this theory tonight after work. i also tried a 1" bulkhead, and the outside threads are 1 1/4"..so it looks like this theory is vaid for any bulkhead size..just add 1/4" and use the outside threads instead of the inside. use some teflon tape as well on the outside threads, maybe even some silicone just to be sure the connection is solid and water tight...

I am trying to do this because my tank was predrilled for only a 1/2" return bulkhead fitting, and yet the drain line is 1/5", and all my pump plumbing is all 3/4"..so i didn't want a 1/2" bulkhead to be the bottle neck in an all 3/4" plumbing project for the return line.

the other option is to redrill the tank for a 3/4" bulkhead, but i am scared to drill it, and since i didn't order a 3/4" hole pre-drilled, any changes will void the clear-for-life acryllic tank guarantee. i should have chosen the 3/4" return line bulkhead drilled when i ordered it, but i had no idea that after awhile i would outgrow the 1/2" line so quickly when i got a bigger 3/4" return pump.

[100_corner_pent]

this is bad info, sorry, it only worked on my 1" bulkhead, my 1/2 and 3/4 bulkhead outside threads are not useable...