By Alan E. Opdyke
In my fish room I have spent a lot of time watching fish and in my own way studying their behavior as related to water changes and filter changes. In reference to filter changes I have actually seen a tank of fish “clamp up” after the filter in the tank was swapped for a fresh filter. For a long while I would take a piece of the dirty filter floss from the existing filter and place it in with the clean floss to start a bacteria bed in the new filter to keep this from happening. Most of the time it worked.
Then I decided to go to two filters per tank. This allows me to always have a “seasoned” filter in the fish tank. I never change them both at the same time. The additional benefit I just recently realized is I now have two streams of bubbles hitting the top of the water expelling more gas from the water and causing a greater turbulence in the tank which I think is good for the fish.
I use a round filter made by Lustar. They have three sizes available. The one they call large is actually their middle size. This is the one I use in my ten-gallon tanks. I use a small amount of dolomite to help keep the PH at a level slightly above 7.0 and filter floss. On filter floss I buy the 100% polyester pillow stuffing from Wal-Mart at a considerable savings over the stuff you get from the pet supply or aquarium stores. Obviously, I never change filters and water the same day and, as I mentioned above, I never change both filters at the same time. In fact I space them out as much as possible. I also use the routine of not replacing filters on any kind of weekly or bi-weekly schedule. What I do is watch all my tanks and when the filter itself has a very irregular bubble stream I assume it is getting clogged and I swap it out.
For cleaning filters I soak them in a mixture of hot water and bleach in a plastic pan for 24 hours or so and then rinse thoroughly and allow to completely air dry before using them again. I have 60 tanks with two filers each and I keep sixteen spares to swap out as required.
This system works great for me and I have minimal amount of deaths, rarely have clamping, and (knock on wood) no diseases.