couple of options..... I've been dealing with the same thing.
how much room do you have left in your last(pump) chamber? If you have all that is seen in the pic, then get some glass cut and replicate the 2 baffles for a total of 4. this will work nicely.
if you use the middle chamber as a fuge, then once it has a bunch of macros in it, it'll reduce the bubbles too.
I used filter floss on the intake side, (not sure if this is recommended, but I plan on changing it out often). I cut a piece the dimensions of the 1st chamber and put a hole in it for the pipe to run through. the floss just lies on the surface of the water and cuts down many of the bubbles being created in that chamber. it's much less bubbly heading onto the next chambers, you can even put some floss between the last baffles, but I think its something that will need constant supervision and maintenance to avoid potential nitrate build up and possible water level changes.... dont want your return pump running dry.
Ryan
