I have replaced my filter a bunch of times, here's a couple tips -

- to get rid of air bubbles in the filter, when you first put it into the water angle the filter and bubble tube sideways and let all the air out of the filter, then attach it to the bottom of the tank
- I don't change my filter every month, usually every 2 months, unless for some reason my tank is really dirty... like when my daughter got into the fish food and dumped the whole jar in the tank (Posted on 11/21/09)