Tiny Bubbles on Top of tank?

[Mercury2234]

Hey guys,

Have a tank about 30 gallon, with an Emperor filter 280; I am noticing lately that tiny bubbles are appearing at the top part of the water.

Can anybody shed light on what it means, or rather is it bad for the fish? Whenever, I do a water change, it all goes away, but next day its back on again...

Many thanks

 

[Wretched5705]

Ive actually been noticing that with my tank as well....hopefully its nothing bad

 

[MONSTERUP]

its just oxygen in the water. happens when water is splahing into your tank. happens only by the filter? its normal