Filtration for Saltwater Ecosystems

Adequate filtration is a fundamental part of any successfully maintained saltwater aquarium. Some of the same aquarium filters can be used in freshwater and saltwater tanks, but saltwater aquariums generally need a more elaborate combination of biological, chemical, and mechanical filters.

Wet/Dry Wet/dry filters are a very popular method of biological filtration for saltwater aquariums. Wet/dry filters provide some mechanical filtration but work best in tandem with a mechanical filter. Wet/dry filters provide some mechanical filtration through a fiber-floss prefilter. Water then trickles across a trickle plate, over bio-media, and into a reservoir, where chemical or biological filtration occurs before a pump returns the water to the aquarium. Wet / dry filters do well in any marine ecosystem, provided that they are properly maintained. The prefilter needs to be periodically changed when it is clogged with dissolved solids, and the biological filter media (bio balls) should be monitored for organic buildup. If there is noticeable buildup on the biological media, then it is time to clean them.

Undergravel
Undergravel filters are commonly used in freshwater aquariums, but their use in saltwater aquariums is considered a little problematic.

Undergravel filters pull water through the aquarium substrate and into a filter plate. If undergravel filters are not well maintained, waste can be trapped beneath the filter plate and release nitrates into the water.

Undergravel filters don't work well with live rock substrate, making them inadequate for the filtration needs of reef aquariums. Undergravel filters are acceptable in fish-only saltwater aquariums, but only if the tank is lightly stocked and a regular cleaning routine is followed.

Nitrate Load
Nitrate load refers to the amount of nitrate present in a saltwater aquarium. Nitrate is the end product of the nitrification cycle. A nitrate load that is too high will stress and overwork your fish.

Aquatic plants and algae feed on available nitrate in the water, but excessive algae are a definite sign of poor water quality and a high nitrate load. Test kits are available that can measure aquarium nitrate levels. If the nitrate load exceeds 10 ppm (parts per million), we recommend treating your aquarium with a nitrate reducer and inspecting your filtration system.

Filter Maintenance
Whatever filter system you choose for your saltwater aquarium, regular filter maintenance is crucial. Mechanical filters in particular must be cleaned often - sometimes every day - to prevent captured wastes from dissolving and polluting the water. No matter how expensive or effective your aquarium filter is, it won't last long without consistent cleaning and filter maintenance.