rouble air pressure testing new dwv system

I've had several leaks that I have repaired on my pvc dwv system. I have the vent capped abvoe roof and final pipe capped in basement. I've been out of the trade a while, but I've had more problems with leaks in pvc than I had in my whole apprenticeship. Am I missing something. This is kicking my ass.

The latest is 3 inch couplings have been leaking. I bought new from several places. Am I using the wrong oatey glue? Should it matter? I mean I bought the glue that comes in the 2 pack with the purple primer.

I think I've got all my visible leaks fixed. Does regualr pvc not hold pressure longer than 5-10 mins??? I mean I put 5lbs air on it and in 15 min. its down to almost nothing....

Any idea on best way to spot the leaks? I've been using soapy water spray and I should be able to see or hear that kind of leak, but I dont.... Any new tricks for visual (i was thinking about black light and uv dust (similar to ac tests)?

I was thinking..(danger) If I put a vacum pump on my test rig and run glue on all the joinut should I be able to suck the glue into any leak? Or will I just crush the pipe?

The stuff holds air, how long do inspectors want to see it at 5lbs? Do they time it?

And on top of it all my roof penetrations leak......ARGG.....

test

I don't know why anyone would subject themselves to the trauma of making a DWV air test. The leaks could be anywhere, most likely at the future openings or threaded test plugs. Mr. Bubble will work the best for finding them.