You can clean the inside of your fish tank with some magnets, velcro, and a plastic bottle cap. And to think, when I had fish, I usually just stuck my whole arm in there to clean it! Instructables user TNEN shows us how to fashion this convenient tank scrubber.

Becky Stern

Becky Stern

Becky Stern ( is a DIY guru and director of wearable electronics at Adafruit. She publishes a new project video every week and hosts a live show on YouTube. Formerly Becky was Senior Video Producer for MAKE. Becky lives in Brooklyn, NY and belongs to art groups Free Art & Technology (“release early, often, and with rap music”) and Madagascar Institute (“fear is never boring”).

  • Matt Mets

    Those are wicked cool, I just became aware of them for the first time a few weeks ago. This does seem like a fun DIY project! Of course, I would want to add some automation.

  • Jason

    There’s a small caveat here. But first a quick overview of fish tank water cycles.

    Fish waste contains ammonia which is deadly to aquatic life in concentrated forms. However, there’s a bunch of microscopic critters that feed on the ammonia and turn it into nitrite. Nitrite is still harmful to aquatic life, so a second set of microscopic critters feeds on the nitrite and converts it into nitrate. Nitrate is much less harmful to aquatic life, and it’s also food for aquatic plants (e.g.: algae).

    So, if you find that you have algae growth on your tank glass it’s probably due to rising nitrate levels. The next part of the biological cycle is for aquatic life to eat the algae. And, so the cycle continues.

    However, if you have not added any algae feeders to your tank, you can get fairly excessive algae growth. This can be reduced by doing regular, partial water changes to lower nitrate levels (this water is great for watering house plants with, by the way).

    And now the caveat. If you mechanically remove algae from your tank glass, be sure to remove the device and any cleaned algae from the tank. If you leave it in the tank, the dying algae releases phosphorus which can cause bacterial growth which can also be harmful to fish (and much more difficult to control).

    The solution. Use algae eaters to clean your tank, and if you feel the need to remove algae from the tank glass, don’t leave the device or dying algae in the tank. Also, regular, partial water changes will reduce algae growth.

    Personally, I like algae (as a biological filter and fish food source), so I only clean the front of the tank. When I do this I use a chemically neutral paper towel, so I can get as much algae off the glass and out of the tank as possible (trust me when I say that cynobacterial blooms are nasty. Especially in salt water tanks).