Overflow pipe size

[Alwmh4]

I just bought a tank that came with metric plumbing. Pipes included are 50mm making finding unions next to impossible or about $40 a piece. So I'm thinking of getting an adapter to go from 50mm to 1.5 or 2". Which size pipe should I get of the two?

150 ga tank. So max flow 1500-2500 gph

 

[zesty]

I would think going bigger would be the best, especially on a drain.

 

[racin2438]

Any chance you can switch out the bulkheads to standard size...

 

[zesty]

Good point. That would make the whole thing easier.

 

[Alwmh4]

I honestly don't know. I don't know if they are standard lengths or if what I have is some custom size. I haven't put it all together yet so if I'm to change it, now is the time

I'm switching from a nano w no sump so please forgive my ignorance

 

[zesty]

No worries. Just try and unscrew the nut off the threads of the bulkhead. You have a picture of what's going on?

 

[Alwmh4]

lets see if I can do this right...

 

[Alwmh4]

last photo is turned 90 degrees. sorry.

anyway, id like to be able to change out valves or pieces of pipe in the future. of course gluing doesn't allow. unions are obvious solution just hard to find and pricey for 50 mm

 

[Alwmh4]

If I keep current bulkhead over flow, my options are a reducer to 1.5" or expander to 2". My fear is 1.5 is too small and 2" whould 1. Create more noise 2.unions for 2" (at lowes anyway) are huge so it'd create a space issue and 3. The particular special order piece to expand will add too much length to pipe to be able to attach Union below and then make 90 degree turn