Air Building Up In Powerhead?

[craigybaby37]

knowtised for the last few days my powerhead is building up with air behind the actuall fan that moves the water and every so often it will put out a big burst of bubbles??

just wondering what may be causing this?? and if its at all a problem??

 

[1entra]

is the powerhead submersed under the water?

 

[craigybaby37]

found the problem now........either through water changes or evaporation the water surface was realy close to the top of the powerhead and causing a small whirlpool above it causing the aur bubble bursts......all sorted now.