I had my septic tank pumped and he told me that the baffle was missing on the outlet pipe and could cause a problem with clogging in the leech field. He told me to go out and get a 4" diameter pvc tee and about 18" of straight 4" pvc to attached to the bottom of the tee to go through the scum layer. I did this, but the pvc doesn't fit over the existing ABS black outlet pipe. I am unable to find this black pipe anywhere. What are my options?

4" PVC and 4" ABS (black) pipe are interchangeable in terms of size (so not sure why you have the issue here). They are NOT, however, interchangeable in terms of joining them together... expand and contract at different rates.

In this case, you will be better off purchasing a FERNCO coupling... the all neoprene type with 2 SS bands... see image below. This will work fine as long as the ABS pipe in the tank is actually 4" (if not, just measure the pipe diameter and purchase the correct fernco coupling).

Good luck!

Mark

Why not simply purchase a septic tank Tee.(See image) and connect that onto your ABS pipe? Good luck, Tom