Need help eliminating micro-bubbles


New member
I spent the last two weekends designing and building a new 120 gal sump for my 500 gal tank....just to have my worse nightmare: MICRO-BUBBLES !! I've built many sumps and never had this problem, but never one this large. It may be difficult to explain the details of my sump and a photo probably would not help due to all the visual obstructions, so I will just ask some basic questions.

Does anyone know of any sites or references that give tips on eliminating bubbles and/or building sumps? I'm hoping to be able to just modify something instead of tearing out the whole system (of glass dividers) and starting over. (I put felt bags around return pipes which helped a little but not completely. What is odd is that I can hardly see any bubbles in the last chamber which provides water to the main pump (return to tank), yet there are plenty of micro-bubbles in tank.

I'll attempt to describe the sump for what it is worth. (Approximately 2000 gal/hr flows into a 6' 120 gal tank which is "divided" into 3 main compartments (left to right: A, B, C)

A: DSB with 14" divider
B: Center chamber to receive water; Also, exit for auxillary pump.
C: Set of two baffles (4 dividers) leading to return pipe for main pump to return water to tank. First set is 10"; second set is 6"

Water from overflow dumps approx 1000 g/h into A, and 1000 g/h into B. (Water from A overflows into B)

B has a set of baffles leading to exit pipe for auxillary pump that feeds two skimmers, a separate DSB/Algae filter/Refugium, and soon-to-be frag tray. Water returns to A and B, approx equal volumes.

Water from B flows through 4 dividers (baffles) to main pump.

Although I didn't plan to use felt bags, I did put them around all pipe outlets, realizing that some water would "back up" out of top of bag. This helped a little but still not enough.

My previous sump consisted of two 75 gal tanks connected in series (L shape configuration)...and I had no bubble problems. (I have good reasons for replacing this system, but not necessary to explain).

If anyone has any words of wisdom, references for sump building/micro-bubble elimination, or moral support....these would be much appreciated!

Thank you.