Sump= MICRO BUBBLES (this cant be right!!)

Sounds like you just have too much flow through the sump for the ait bubbles to actually rise out of the water column before being sent back up to the display. Might want to try using a good filter sock on the overflow line, that will give any bubbles more of a chance to escape before passing through the sock. Just remember this will act as a sort of mechanical filtration and will need periodic cleaning. If you go this route use a decent quality sock, one of the thick wooly type.

I'll get one ordered and give it a try

#1 - Rio 2500 pumps are ticking time bombs. You need to replace it immediately with a safer pump. When (not if) it fails, it will fail spectacularly and will nuke your entire reef. The 2100 is just as dangerous, btw.

#2 - a 10g sump is very small, and there is virtually no linear travel time.

The flow through the sump should be 3x to 5x the volume of the display tank. If your tank is a 30g tank, 90 to 150gph is more than enough flow traveling through the sump.

The fact that your return pump sucks the return dry indicates that it is too powerful as well as the fact that the return section is too small.

Filter socks are fine if you set them up correctly. You don't want any part of the sock to be outside of the sump, because it will clog up with detritus and overflow. If the sock overflows, make sure it is situated so that it overflows INSIDE the sump and not all over the floor.

Socks should be swapped out every three days.

Thanks Marc!!

Switched to a Catalina Aquariums 1800 and it works great even in the smallest section so I got my refuge back!!!!

cool jojo..