repairing cracked nipple at pump intake (pic enclosed)

Hello everyone! I'm trying to repair the pump intake to an aquarium calcium reactor. There is a true union (slip I think) with a nipple going into a 3 way elbow. The nipple running between the union and the 3 way elbow is cracked off completely. HOw should I repair this?

I was thinking two ways... glue it up ghetto style. Probably not a good idea because it will have highly alkaline salt water flowing through it. OR using half of a new union and rebuilding the rest of the intake to the pump. I just don't know how to get that air hose into the top of the elbow. Does that look like a standard fitting?

Thanks for your help.

busted calcium reactor

Don't glue it!

As hydroponics and aquariums meld into one hobby for myself, you made my day!
Rebuild it would be the answer.
If you can't find the replacement for the plugged end you could put a cap on it and after predrilling a hole, tap it to accomadate whatever size nipple for the smaller hose you want. The thicker the cap, the more threads you'll have to hold the new nipple in. As you have chemically reative conditions, you may see if there's plastic threaded ones available. If Homers, Nards (Menards), Lowes or a better aquarium supplier can't help you, there's janitorial supply places that service steamcleaners, and pool suppliers (think sodium hypochlorite or calcium chlorite and ect.). Some outfits sell supplies for both and may be a source for ideas where to get specific items. Or considering the price of the standard brass and time expedediency buy a couple as maintanance protocol.
As you probably figured out allready, you have to have a certain amount of surface area available before glue would be viable. And as with any plumbing or electrical design, male to female is the best coupling