are micro bubbles ok?

[j-man]

anyone have problems or read that a large amount of micro bubbles in the tank are harmful. A guy at a LFS said it can cause gill disfunction?
A large amount of bubble are produced as the water flows to the sump, then they get pumped back into the tank by the return pump.

 

[puff(er) daddy]

I don't know if they are harmful but you can add a piece of sponge where the water flows to the sump to prevent the bubbles from forming.

 

[wamp]

They are harmful to certain corals. They can Block pores or get under the corals and cause tissue erosion.
As far as fish.. No clue on that one.