Microbubbles!! Ahhh help!

My tank has micro-bubbles...an I can't figure out where they are coming from!...Its not the skimmer...i turned it off (even tho i knew it wasnt it cuz my fuge/sump has NO bubbles)....Next step was...maybe one of my pipes has a hole and is sucking in air...so I went over EVERY join with silicone (tank has nothin living in it just in case you freak)....and that hasnt seemed to fix my problem either....what should my next step be?? My return line isnt glued together in the overflow box...and the 90degree angle at the top isn't under water...so I think maybe that sould be my next step? Glue that on (even tho its not leaking)....then if that doesnt solve the problem should I replace my lockline?....what if that doesnt work? Could my pump be CREATING the bubbles itself? (its an inline little giant) Please help

 

as there is nothing in there (and even if there was to be honest)

I would do exactly as you did with skimmer and turn off each piece of equipment in turn
until you locate which one is the source of the bubble production
leave each one off for a few minutes, to allow the already accumulated bubbles to dissapate, turn back on and see if new bubbles are created

once you have isolated the start of the problem, a solution will be easier to put into place

Steve