Microbubbles with unknown cause

[Dom]

I would suggest checking your return plumbing. I had a similar issue where the cause was the check valve.

I disassembled to clean it. When I reinstalled it, I didn't tighten the collar all the way. This allowed air to be drawn into the return line and created micro bubbles.

 

[Rmckoy]

You need to take the blades out of each side and switch them to the other side. Read this thread to the end, and you will see that this person had the same issue, https://www.reef2reef.com/threads/micro-bubbles-from-gyre.449345/

Does the gyre not have a setting to run reverse ?

 

[Phildago]

Does the gyre not have a setting to run reverse ?

It does. It only goes for 10 min though

 

[sarcophytonIndy]

Sorry if I messed you up. Just trying to be helpful. I don't have a gyre, but I have heard about them causing cavitation if assembled incorrectly, usually after a cleaning.