Can you use pipe dope on Pvc pipes when working with saltwater fish?

Answer 1

I would use Teflon tape instead. That way nothing should get into the water. If you have never used it before, hold the threaded pipe in your left hand and wrap the tape over the top of the threads and around several layers. By doing it this direction, the tape will stay in place when you screw it into the fitting.

Teflon tape only works on threaded fittings. using pipe dope is absolutely fine to use on fish tanks, just be sure to let the dope cure perhaps as long as three days. also take care to use the correct type of dope, their are many. if in doubt test the fittings in salt water before using.

If you are just pressure fitting the pieces together, glue them. Pipe dope may seal the connection for a while, but it will eventually leak.