8. Choosing the Right Filter
The single most important factor in successful fish keeping is water quality. Fish and other livestock, including invertebrates and plants, are captives in a tank environment so it is imperative that keepers accept the responsibility to ensure that their environment is clean, healthy and free of disease and disease-causing situations. Most new keepers, and some seasoned keepers as well, are unaware of how quickly ammonia can pollute an entire tank and kill fish within hours. Everything can look great but within a short span of time, everything is dead.
With the wealth of information, equipment and products available today, fish keeping should be easier and more successful than ever, but, unfortunately, too often keepers ignore the basic rules and face problems. Equipment and products may come and go, but the science of maintaining a clean, disease-free environment never changes.
Filtration is critical to water quality. A filter is a compact unit packed full of high surface area media where millions of beneficial organisms flourish. As the aquarium water, filled with fish waste and other debris, passes through the filter these organisms ‘consume’ the wastes, thus eliminating the pollutants that could eventually kill the fish. The market is saturated with filters of all types and choosing which type is right for you is an important decision. The first rule of fish keeping is – understand the Nitrogen Cycle. The second rule is – buy the best filter you can afford. Every single time your tank has water quality problems, the solutions are associated with these two rules.
Filter Types and Ratings
The filters types below are described and are given a rating system from 1-5, 5 being highest based on the criteria listed below. N/A means that feature is not applicable to that filter type.
Chemical Filtration – space to accommodate carbon, resins, phosphate removers, etc.
Mechanical Filtration – capable of removing actual particulate material
Biological Filtration – active surfaces for reducing ammonia and nitrite
Ease of cleaning
Economical to use
Packing Life – time between cleanings and media replacement
Aeration – capable of oxygenating the tank water
Ease of setup
Undergravel Filters
The old standby. People either love them or hate them. Undergravel filters have huge surface areas for biological filtration and can be operated with either airstones and an air pump or powerheads. When using powerheads, remember to use the aeration feature on powerheads or an airstone. These systems are occasionally the only filters that will fit the application. The down side is without frequent gravel cleaning via water changes, undergravel filters are a problem waiting to happen. Always use additional filtration, whenever possible.
Hanging/Box Filters
Probably the most popular type of filter. Although easy to both install and maintain, these filters require frequent cleaning and pad/sponge replacement. This is, however, a fairly easy task. Remember, these units hold the aquarium away from the wall 3-5 inches. For better water quality, opt for multiple box filters instead of bells and whistles. If one filter goes down, there is a backup. Never change both pads in a double padded filter or both filters in a dual box filter setup at the same time when cleaning. Alternating the media replacement preserves important bacteria. Some filters have room for additional bio media which should be used. Some have aeration features – moving surface water also aerates but remember, heavily loaded systems benefit from a decoratively placed airstone.
Prefilters, like the AquaLife Prefilter, fit most models and increase biological and mechanical while preventing small fish and invertebrates from being injured. Rinse these filters at the first sign of reduced flow.
Internal Filters
Many filters fall into this category. They include internal sponge, powered internal, and internal box or canister filters – air powered and motor powered. Breeders love them. They are easy, low cost, low hassle filters. They all aerate and biologically filter. The old fashioned, floss-filled internal air driven box or canister filter is great for breeding tanks, small tanks or for quarantine tanks. Internal filters can be packed with a range of filter media for biological, chemical or mechanical filtration depending on the application. Because they operate by forced air, they both aerate and filter the water. If a larger tank is having problems, add an internal filter filled with high quality carbon and floss. The disadvantage of filters in this class is size – they are simply too small to handle much fish load, must be hidden and take up floor space.
Canister Filters
Canister filters are quiet running filters with high biological capacity and should be considered second choice to trickle filters. Canister filters have both pros and cons. The better designed units have good chemical filtration because no water by-passes the media. Canisters are also ideal for planted freshwater systems or when trickle filters are simply too large for the application. Canister filters provide long service life if packed properly with quality media and are economical to operate compared to box filters. Remember, these filters are closed systems and usually have lower flow rates. Use a small air pump and a decoratively placed airstone in aquariums without live plants or in saltwater systems without protein skimmers. Air pumps increase oxygen levels and act as a fail-safe in the event of a filter failure. Choose a canister filter one size larger than manufacturers recommend for heavily loaded systems or for saltwater. Larger filters are more efficient and have higher flow rates. Stay away from filters that use small internal baskets for media. Better units have either large internal baskets or trays and can be completely packed using 99% of their space for media.
Trickle Filters
This is the most important decision keepers make. Saving a few dollars at this stage can mean countless dollars in fish losses. Under-filtered tanks cause problems again and again and make fish keeping a headache instead of a pleasurable, exciting hobby. Trickle filters are the best choice for tanks above 30 gallons. Good mechanical and biological filtration maintains robust oxygen levels and keeps harmful fish waste and other decaying debris from polluting the water and killing fish. Trickle filters, because of their size and expanded biological surface area, perform these tasks better than any other form of filtration and should always be considered the first choice. Trickle filters are more reliable and easier to maintain. Since there are no costly cartridges to replace, trickle filters are also more cost effective to operate.
Protein Skimmers
Protein skimmers remove proteins and waste aiding in algae and water quality control while lessening the need for carbon use in fish only systems. They are not needed for aeration in a system with a quality trickle filter. Skimmers help in phosphate removal and should be considered mandatory to all “reef” setups. Some of the “Mud Type” systems do not call for them, however, they could be added if needed. Skimmers increase the efficiency of any system. Remember, all skimmers require cleaning and regular checking.
Ultraviolet Sterilizers
Technically not filters, UV sterilizers certainly affect water quality. These units kill unwanted bacteria and parasitic pathogens thus reducing chances of disease outbreaks or spreading. They also help clear bacterial blooms that sometimes cause white, cloudy water. No store central systems go without sterilizers and that speaks for itself. These, like protein skimmers, can be added at any time. Some “reef” keepers install them in case a problem arises. Sterilizers can be turned on when adding new fish or as needed.