There are three main types of filtration: chemical, mechanical, and bio-filtration. Most filters on the market are sold as a three in one filter and yes they are but you must look at them to see how well they work at each before buying one.
Biological filtration removes ammonia, nitrite, and nitrate from aquarium water by way of positive bacterial colonies that convert it, through oxidation, to harmless gas. Not all bio-filtration is the same, if the filter oxygenates the water then it will only convert ammonia, to nitrite, to nitrate. If nitrate is left to build up in the system then algae will grow out of control and crowd out the tank. For bio-filtration to remove nitrate there must be a place with low oxygen like live sand or live rock and to let you know bio-balls does not remove nitrate nor a bio-wheel.
Mechanical filtration is performed when water passes through a filter's foam pads, catching particulate matter like uneaten food, waste and decayed plants. You must clean the foam pads often or your not filtering.
Chemical filtration refers to any filtering substance that is designed to change the chemical composition of the water, but most often refers to the use of activated carbon or other cleaning resins. Activated carbon pulls dissolved organics from the water by adsorbing them. You must replace the cleaning resins and activated carbon often or your not filtering.
A protein skimmer or foam fractionator is a device used mostly in
saltwater aquaria to remove
organic compounds from the water before they break down into
nitrogenous waste. Protein skimming is the only form of aquarium
filtration that physically removes organic compounds before they begin to decompose, lightening the load on the biological filter and improving the water's
redox potential. Although the process of
foam fractionation is commonly known for removal of waste from aquaria, it is, in fact, a rapidly developing cess">chemical process used in the large-scale removal of contaminants from wastewater streams and the enrichment of solutions of biomolecules.
I will say a must have filter.
Bio Wheel power filter and cartridge filters So these filters are small bio-filters that for the most part are lacking the low oxygen to get rid of nitrate so some other filter is need for this task. The cartridge filter are very good chemical and mechanical filtration. A bio wheel for what it is it is very compact and does help with ammonia, nitrite and for its size is a good chemical and mechanical filter.
Sump / Refugium filtration A sump is nothing more than an extra water containment area usually set up underneath an aquarium where you can place equipment, provide the aquarium with various types of water filtration, add top-off water to the tank and perform other maintenance tasks. A refugium is separate tank, or refuge, attached to the main aquarium system. The purpose of a refugium is to serve as a breeding ground for algae and tiny invertebrates. They are able to grow faster in a refugium because there are no predators to eat the algae or inverts. These tiny inverts such as copepods can eventually make their way into the main display tank where they will provide food for corals and fish. Mandarin fish feed almost exclusively on copepods and will thrive in aquariums with refugiums. And the algae can remove waste from the water in the confines of refugium without becoming a problem...
