Bulkhead Plumbing question
 

i am just in the middle of setting up my first saltwater tank and kinda stumped at my overflow plumbing.
I want it to go from my CPR overflow with 3/4" bulkhead fitting to an union and to my 3/4" PVC tube pipes. however, the problem i am having is that the 3/4" threaded bulkhead is not fitting any union i can find at my local Home depot. it seems the bulkhead is not a standard size i can get. if i am correct i need a reducer from the bulkhead to the 3/4 union but the 1" reducer to 3/4" didn't fit the threads on the bulkhead...is this confusing anyone? so my question now is what are my plumbing options??? and what is the size of the bulkhead threads?

here is a link of my bulkhead
http://www.mops.ca/skus/bh/BHRB-270577.jpg

edit: sorry is not threaded inside only threaded on the outside

based on the link that is a 3/4 threaded bulkhead, but a 3/4 nipple cut it in half, thread inside the bulkhead and adapt to a 3/4 union. should be pretty easy.

If you are trying to thread over the bulhead you likely will not find the correct thread.

sorry mr. OM is not threaded on the inside only on the outside it has the threads. but i guess i can still do the same thing. use a 3/4" pvc pipe slip it in put the union on...so i guess there isn't anything that will thread over the bulkhead to a 3/4" reducer?
thanks for the help btw

Use the slip slip fittings as you mentioned, typically good bulkhead fittings will be both left handed and buttress threads for best results, likely the one you have is just a generic tank adapter and the outside thread isn't likely to be of any standard engineered thread.