Fish Tank Filter Troubleshooting

Proper water filtration is critical to the success of your aquarium whether it is fresh water or salt. Keeping a close eye on the conditions in your tank will give you valuable clues as to whether your filter is doing its job or if you need to troubleshoot it. Colored water, debris and fungus can all be indicators that your filter is not performing how it should.

  1. Types of Filters

    • Under-gravel filtration filters from under the gravel at the bottom of the tank. They are fairly adept at biological filtration, that is changing ammonia and harmful nitrates into something more benign.

      Hang-on-back filters do a good job at mechanical filtration--removing particles from the water and chemical filtration. They are fairly inexpensive and easy to use.

      Sponge filters are easy to clean and inexpensive. They can be a great addition to both large and small tanks.

      Canisters are the most popular filters for large aquariums because of the large capacity. They do not need to be cleaned as often but regular maintenance should not be overlooked.

    Preventing Problems

    • Under-gravel filters can behave sluggishly if too fine of sand or gravel is used. Too coarse of gravel will also prevent proper circulation. Proper cleaning includes removing organic matter from near the lift tubes and making sure that the gravel is deepest in these areas.

      For hang-on-back filters, ensure that all parts can turn smoothly and that no gravel or organic matter is blocking the intake or moving parts. Clean the filter regularly to prevent blockage.

      Canister filters can have problems when air bubbles get inside the unit. Make sure there are no air bubbles before starting the filter.

    Troubleshooting

    • Start with the basics. Check that the filter is plugged in and turned on. Ensure all tubes and intake areas are free from blockage. The filter should be cleaned and replaced. For a hanging filter, the impeller blades should spin freely. Check for loose gravel or other debris if they do not. Make sure that the water in the tank is deep enough so that the filter is not sucking in air instead of water.

      If your filter is clean and clear of debris, all moving parts are working and it is both plugged in and turned on, you may have an electrical problem and may need to replace the filter or the electromagnetic coil inside.