JimM

The micro bubbles could be from a few different things. I see in your sump design that you dont have a bubble trap on the first series of panels, turning that into a bubble trap could help. If your source is the skimmer. Another source could even be the return pump itself, I've had return pumps break just a little bit on the volute and when the water level gets low enough they will suck a small amount of air from the surface which caused micro bubbles. Are the bubbles you're getting sporadic or are they constant? Do you get allot of them or just enough to notice?

Welcome!

Tom

are the micro bubbles in the fuge? kind of curious why you split the return water, running it all into the skimmer section would have given you to traps before the pump chamber, usually you only split it like that if the fuge and skimmer are at opposite ends of the sump with the pump section in the center. Is the pump externally or in sump? If the intake of the pump is to small or to restricted and creates a negative pressure before the intake it can create microbubbles without drawing any air. If you are not seeing them in the fug and pump section this is where i would start looking. Also make sure none of the line loc fitting are above the water line in the tank as they could allow a ventura affect as the water passes thur them

Thanks for the Welcome!
Wiorkaholic: The skimmer (an octopus) doesnt seem to be putting out much in the way of bubbles. Your comment about the pump is interesting... it is an inexpensive one and perhaps that is the culprit. The bubbles are very tiny and present in the display most if not all of the time.
DJ: Honestly, split the return water because I didnt know any better. Just starting out and read / watched some of the designs we could find on the internet. I thought I had learned that the fuge itself should have some agitation from the return to keep the macro algae happy... but I really cant recall for sure. The return section is always under water... well most of the time anyway if my son remembers to add the top off... but were right in the middle of making an auto top off setup that should cure that... if he remembers to fill the source once a week!!! I will look for those other problems you describe and....
Thanks very much to both of you for the input!
Jim

Jim, well here's what i would do. Just as a process of elimination. While there are microbubbles visible in the tank, turn off the skimmer for a couple hours and then see what happens to them. If they go away, fire the skimmer back up and see if they come back. i've also found that with some skimmers (mainly found this with vertex IN series skimmers) if there is a clog in the air intake the skimmer will not pull much air but will force allot of bubbles out the water return from the skimmer body. If you're able to rule out that its the skimmer then I would see if you could borrow a return pump (doesn't have to be the exact right size, just something that you will able to hook up for a couple hours) Then swap out return pumps and see if there is a change because honestly out of all the times i've messed with tanks with this problem its always been one of those two.

Tom

Take a flash light and look at the water in the return zone. If it is bubble free, the problem is at the pump or thereafter. If you see microbubbles in the return zone, then you need to stop them before they can enter.

Thanks a lot guys... now I have a good experience based plan from which to work this out!