magnum as a diatom

[gadgetthecat]

I want to use my magnum as a diatom filter, but have a problem with air getting into the canister, how can I stop this??

[Lady Hobbs]

Sounds as you have a bad seal. try rubbing some vasoline on it.

[cocoa_pleco]

yep, rub lubricant on the O-ring and check that no air gets into the intake

[Sasquatch]

Magnums can be a little finicky when you change the cartridge inside them. Make sure that there are no air bubble under the canister cover. You have to fill them until they are almost overflowing and make sure there is no air traped under the internal flow diffuser.

The D-rings are also a little bit of a pain. I found that they crack easily, which lets air into the filter. If it's cracked, damaged or brittle, replace it. Vaseline can be a good stop-gap measure, but eventually you'll have to replace the d-ring.