dont fret so much about it. you just need to get it dialed in and you will be good. the microbubbles you are getting are coming fromteh skimmer and the flow from teh tank. I recommend you open teh flow from your overflow box wide open. then close the valve on the pump a bit at a time till you get the flow you want. the bubbles will slow when you throttle it back. your HOB overflow will only remove what your pump puts back in provided you have no air in the U-tube.
as for the noise, yes, they can make that noise. you should try it with twin 1 1/2" drains at 2000gph! sounded like the toilet on a cruise ship. I added a Hofer Gurgle buster. it is a home made devise that completely silenced the returns on my tank. Go look it up. it is small and can fit right in your overflow.
you are just a few tweaks away from success. we have all been there. unfortunately for many of us, sites like this werent around back then right bill?
Heck, There wasn't even Computers around when I started Reefing, We had to build every thing DIY back then, No store bought stuff to be had LOL
Bill:dance:
Oh yea, and FYI, they dont like URL's in your signature. they made me remove mine.