Aquarium Filter Basics


Aquarium filtration is key in the well being of any aquarium. Aquarium filters can remove most biological waste from your aquarium. However there is one thing that aquarium filters cannot duplicate, water changes. Weekly water changes are necessary despite some products insisting otherwise. Water changes remove waste that cannot be removed by any existing aquarium filter on the market today. As well as provide trace elements that may be beneficial to your plants, corals and fish that are depleted slowly as time progresses.

Canister Filter

There are five primary filtration systems available to hobbyists: undergravel, wet-dry, hang-on-the-back, canister, and box. The undergravel filter can be limited but still remains a cheap, reliable filter system. Box filters have proven ineffective because the water is able to flow around the filter media. Hang on-the-back filters are cheap and great mechanical filters, but overall the canister filter takes the win. The canister filter is the most efficient chemical filter as well as a great chemical filter. The wetdry filter works on the concept of biological filtration as well as the direct loss of ammonia from air exposure.


Hang on the back filter

The most common chemical filter product is activated carbon. Activated carbon should be a little bit bigger than the size of a pin-head. When active carbon is washed and dried it should be dull, not shiny. When placing active carbon in water for the first time it should make a hissing sound. Carbon will float at first and sink with time. Activated carbon is the most popular chemical filtration. This is due to its effectiveness as well as its low price. Great homemade filters can be made using activated carbon in combinations with other chemical filters.


Box Filter

Chemical filtration is not limited to active carbon.  Synthetic adsorbents such as ion exchangers and zeolites can be useful. Zeolites are white, dusty clays, that are best for removing ammonia. Zeolites are great but do not work in saltwater aquariums or any aquariums contain even small amounts of salt. Zeolites cannot remove nitrates. Synthetic ion exchangers can control ionic balance in freshwater aquariums, remove ammonia, nitrite, and nitrate. In marine water, ion exchangers can remove some nitrite and nitrate, but have no significant effect on ammonia.They can also be used to prevent ionic imbalance Ion exchangers are phenomenal at removing organic waste in both freshwater and saltwater aquariums.


Undergravel Filter

There are three types of filtration: mechanical, biological, and chemical. Mechanical filtration is the process of removing particles from the water using floss or foam. Biological filtration is the most important type of filtration. This Biological filtration is the removal of ammonia and nitrite using the Nitrosomonas and Nitrobacter bacteria. The best aerobic biological filter is the wet-dry filter.

The most reliable aerobic biological filter is the wet-dry. Anaerobic biological filtration converts nitrate to nitrogen. Chemical filtration is the removal of biological waste via active carbon or Purgien. The most important function of chemical filtration is the removal of nitrogenous organic waste. If chemical filtration is not sufficient, biological filtration may not be strong enough to uphold the water quality.


Wetdry Filter

The most familiar chemical adsorbent is activated carbon. Activated carbon should be a little larger than pin-head in size. When washed and dry, it should be dull and not shiny. When placed in water, it should hiss. It should also tend to float at first. A good quality active carbon will be hard and nut crumble between your fingers. Make sure your filter is not full of charcoal. Charcoal looks the same as active carbon but can be crushed easily and will not hiss when entered into the water. Activated carbons come in a variety of shapes sizes and efficiency. Avoid Coconut carbons, these carbons are often used for gas filtration rather than water filtration. The best carbons are usually created with bituminous coal and have high porosity and low density. Make sure your carbon has a low ash content so it does not affect your aquarium PH. All activated carbons will release phosphate (Many brands will deny this). Provide only carbons that leach the least amount of phosphates for saltwater aquariums containing reef.


Purigen-base Filter