Leak at joint of filter outlet & return pipe

[azanclay]

I have a leak where the outlet coming out of the filter and the return pipe. See attached picture. I just noticed it last week.

At the joint where the filter inlet meets the pipe coming from the pump, there is a silicone caulk around the outside of the joint, but not where the filter outlet meets the return pipe. Should i do the same at the filter outlet?

 

[Texas Splash]

You can't apply a caulk to the outside, it will just fail. Best repair is to disassemble the pipe adapter from the filter inlet/outlet, apply new product to the threads (i.e.. Teflon tape, plumber's goop, etc) then reassemble.