I have a leaky connection. I have a PVC pipe (2" sch. 40) that goes into a PVC elbow (2" sch. 40), that is leaking right at the connection. There is some water pressure in the PVC. I built a filter system for a fish tank and there is a water pump that pushes the water through these pipes, and unfortunately, I don't know how to stop the leaks. Nor do I know the PSI, but I assume it is very low. I tried using a rubber coupler with hose clamps, but the leak has only slowed, not stopped (I got a "reducer" and fitted it over the pipe and elbow, then tightened the clamps as much as I could, but after awhile the water seeps out). Some people have mentioned a device called a "Union," but I'm not certain how / if this can stop my leaks. So, how can I stop the leaks, without permanently sealing shut the connection?