My BakPak produces micro bubbles too, but it has not been running very long. From what I understand, it is normal to have the bubbles in the beginning and they should reduce in time.
Mine also came with a sponge that goes in the vertical part of the outlet pipe. It is about 4" long, and it's shaped like a tube cut in half. That is supposed to cut down on the bubbles also. Personally, I have not tried it yet. I'm waiting until I'm finished cycling. The only thing about the sponge is it's kind of a pain to get in and out of there and you have to make sure you keep it clean.
Are you using the blue bio-bale material? If you are not, I believe there are some plastic baffles you can put in place of it which is also supposed to reduce the bubbles. I am not using anything in that area because I have my heater there.
HTH
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