Air in Filter

[Richard Dowling]

Hi All, I've noticed in the last day or two that my Tetratec EX1200 extermal filter is pushing bubbles out constantly (which is annoyingly loud). The filter usually does it for a few hours after you clean it because obviously it's full of air when you turn it on. But this time I havnt had it open for quite some time and its doing it all day. I've given it a little shake to dislodge air but it just keeps going! How can air get into a sealed system without water getting out?

Any ideas what the problem is?

 

[Julian]

Probably a small leak on the intake side. With water flowing downwards, this will create suction which sucks air in (as long as the leak isn't very big). On the output side, if you have a leak you'll get the opposite - drops of water.

My ehiem intake (installation set 2) has a small cap on it, if it's not screwed on properly it sucks air into the intake pipe. It could be any joint on the intake side so start here.

 

[sciencefiction]

Is your water level a bit down? As Julian says there could be a crack/gap on the intake above the water sucking in air. It happens to mine(different brand) if I let the water level go down.

 

[Richard Dowling]

I dont have any cracks on my intake (its glass and appears fine, the vents are below water level), however, I decided to take my hoses off and clean them because they were covered in algae, whilst doing that I noticed that one of the threaded connections on the outlet hose had dried scum around it so it seems that has been weeping ever so slightly, so perhaps that is where the air was getting in. I have tightened everything up and the problem seems to have died down over night! My filter is getting on a bit, perhaps I should expect these things.