How to Clean a Fish Tank...

Step 8 Tend to filter...

In an undergravel filter, there is a filter cartridge that is filled with carbon that the water flows through. My tank has two of these cartridges. On the instructions for the filter, they recommend that you change these every two weeks. In my opinion, this is overkill that could get very expensive. I have discovered that I could get by with replacing these every two to three times I clean my fish tank. On the cleanings in between, I take them out of the filter and rinse them out. As they are cleaned, the water flowing out of them will initially be dirty looking, but once it starts flowing clear, I stick it back into the tank.

I have strong fish. Goldfish and guppys seem to be able to live in just about any conditions, so this technique works just fine for me, and the filter still works. If you have more sensitive fish, try this at your own risk. If in question, follow the directions that came with your filter.

I only replace the airstones if the flow of air bubbles are as strong as normal. I replaced one airstone in this cleaning.