I don't belive it's microbubbles. I have the returns from tank and skimmer going through 100 micron Filter socks. And as far as the glue goes, : I used pvc primer and cement. Waited about 24hrs for that to dry filled tank with ro water . It was crystal clear, added instant ocean salt it was cloudy for a few hours then crystal clear again. Let the whole system run like this for 2 days to check for leaks etc, and noticed by the next day the water was really cloudy. Still a mystery to me. I think if it were a bacteria it would be getting worse but it's not. Anyway I didn't add anything to put bacteria into the tank. Is there any product made to fix a cloudy tank? Thanks for everybodys input on this...