I've tried epoxy repairs a few times -- and seen them tried many more -- all without long term success.

PVC welding works, but that's tricky and requires expensive equipment to do well.

Of course, the best method is to replace the Tee, but it sounded like that was also a major effort. Unfortunately, most pool guys are either poor plumbers, or else just don't give a s###.

One of my pet peeves over the years were installations that required major replacement in order to effect a minor repair!