fish in an aquarium

If an aquarium has a beating heart—it must be the filtration. Without filtration, the live animals in an aquarium will not survive very long. It is the one thing that can restore polluted water to healthy water without a water change. But, no matter how good filtration is, it cannot stem the tide forever. Eventually, the water in an aquarium must be changed. 

If you want an aquarium to be healthy, you must perform frequent partial water changes. This technique, coupled with good filtration, is part of the cornerstone of maintaining a biologically stable environment. Once you add two additional building blocks to the equation, you should achieve aquatic nirvana: first, your selection of fish must be compatible with each other and the size of aquarium being used; second, your feeding regime must include the proper foods in the proper quantities. Get these four things right and success should be guaranteed. 

Be aware that the best filter in the world is not capable of doing the work on its own. With that said, a customer should always be directed to a product that fits his individual needs. Don’t sell a filter recommended for a 75-gallon tank to someone with a 30-gallon aquarium. A little overkill is acceptable, but there are limits. For example, if the product box says “up to 75 gallons,” it will be fine for a 50- or 55-gallon tank, but it is too big for a 30-gallon tank.

I have been keeping fish since 1965, first as a hobbyist, then as a fish breeder, then as a retailer, then as a fish farmer and finally back to the retail trade. To be perfectly honest, the innovations I have seen in aquarium filters over the years have been both dramatic and traumatic. Let me explain. 


Under-Gravel Filter

Circa 1965, the item of choice was the internal box filter, followed closely by the under-gravel filter. These worked great in moderately stocked tanks up to around 55-gallon capacity. There were no power-driven external filters at that time, but there were air-driven filters of this type. To put it judiciously, these were only adequate for tanks of 30-gallons or less which were thinly stocked.

The great thing about air-driven internal box filters was they provided plenty of water movement from the substrate to the surface. If you filled the clear boxes with activated bone charcoal, filter wool and a fiber pad to sit the charcoal on—you were good to go. Just keep an eye on the filter wool and when it got dirty, it was time to change the filter. Under-gravel filters were all the rage. They were run by air until someone got the bright idea of putting a powerhead on each lift-tube. Then they pulled more water through the substrate, but the aeration feature was lost. Cleansing under-gravel filters required using a siphon hose with a gravel washer on one end. It was simply an underwater vacuum cleaner. 

The technique was easy, but it proved too exotic for some people. Sucking on the end of a siphon hose without the proper technique would result in a mouthful of aquarium water. Regardless, the wonderful benefit to the under-gravel filter was that the aquarium hobbyist was doing two things at once: cleaning the filter, which was actually the gravel, and changing water. What could be more efficient?


Hang-on-the-Back Aquarium Filter

Evidently, the companies making filters were not particularly concerned with auxiliary sales of related materials. Instead, they concentrated on making better, more efficient mechanical filters. 

The next innovation was the “hang on the back” aquarium filter, powered by a fairly large motor, which stuck up above the tank by several inches. The filter bed was a large flat plate inside a rectangular plastic box. Two (or more) siphon tubes pulled water (courtesy of the motor) up out of the aquarium onto the plate, which was covered with a fiber pad, overlaid with activated bone charcoal and filter wool. These siphon tubes had large slotted openings that allowed large debris to pass through and be deposited and trapped in the filter wool. They virtually never clogged up because the water passing through the motor and back into the aquarium was pulled from under the plastic plate. 

Of course, profit incentive knows no bounds, so someone decided the cosmetics of the ugly pump being visible from the front of the tank were too much for the public to deal with.


Canister Filters 

Next, companies determined that canister filters were the way to go. They would sit under the tank hidden by a wooden cabinet stand (which few people had at the time) with only umbilical in-and-out hose connections to the water: one tube out and one tube in. The canisters were filled with two or more trays full of things like sponge pads of different densities, bags of activated carbon, ceramic rings cleverly called a variety of names like bio-rings, plastic balls even more cleverly called bio-balls and a variety of bio-matrix products. All of these were sold right along with the canister filters. Of course, these required either cleaning or replacement on a regular basis. 

Since the filter itself was out of sight, it was also out of mind. With the intake underwater and the return frequently underwater, people would typically not discover the filter had slowed down to a trickle until the fish were in distress. Then came the fun of disconnecting the canister and taking it to a sink to take apart so it could be cleaned.

Unfortunately, because the hoses were attached to the top of the filter, the tops could not be moved on some models. Then, there was always the problem of restarting the filter. If there was not sufficient water in the canister, the impeller in the motor would frequently fail to start turning. 

Now the thing about a canister filter is that it must have a motor strong enough to pump the necessary head (or the height a pump can raise water up). If the tank is really tall or sits on a tall stand, it may significantly reduce the discharge of the pump. This means the filter is not “turning over” the volume of water in the system at an acceptable rate. Poor filtration results in poor water quality. It’s a vicious cycle.


Wet/Dry Filtration

The next stage of evolution in aquarium filration was the wet/dry filter or sump. This is basically a plastic or glass box (tank) that sits under the aquarium (usually inside a cabinet that hides it from view). The wet/dry filter has various compartments that perform different functions. These include a water input from the aquarium, micron filter socks through which the water passes, a refugium area where pollutants are removed by a variety of living organisms, a bubble trap to keep air from being returned to the aquarium, and finally, a pump chamber that houses the pump that returns water back up into the aquarium. 

Unfortunately, wet/dry sumps and the equipment necessary to run them can cost as much or more than the aquarium itself. Although wet/dry filtration is extremely effective and efficient, it is used almost exclusively in: (1) large living reef aquariums or (2) giant freshwater tanks of 200 gallons or more. Also, in order to use wet/dry sumps to best advantage, a tank should be drilled, which is another expense and creates a number of nightmare scenarios of leaking seals and hoses with pinhole leaks.


Hang-On-The-Back Waterfall Filters

Finally, for tanks of average size (40 gallons to 125 gallons), there are the hang-on-the-back waterfall filters. These have a low profile so they don’t ruin the feng shui of the surrounding environment. They come in various sizes, various designs and with a number of clever devices, such as spinning biowheels, spray bars to generate the movement of the wheels, waterfall water return and proprietary filter cartridges through which much of the return water must flow. This water is the only water that is actually subject to filtration. 

Since this is a waterfall type of filter, the water is sucked up by a single siphon tube fitted with an endcap with tiny slits. Any large pieces of debris cannot be allowed in the filter, since the water goes straight to an impeller chamber before it is cleaned. Once the impeller is compromised, it will not pump fast enough to pass water through the filter pads or turn the biowheels. In short, the engineering on this type of device needs to be re-calibrated. 

If you believe you can make your money on filtration products by selling the proprietary cartridges, be aware that cyber-companies sell them at a fraction of what they go for in brick-and-mortar locations. 

Filtration is a difficult category for you to make good money in, unless you study the products and their efficacy very carefully. My recommendations are to only sell filters you have tested and that are made by companies who support local merchants, not the chain, big-box and cyber-sales companies. Good luck, I hope you clean up—literally!  PB


Edward C. Taylor has been in the pet industry for more than 40 years as a retailer, live fish importer and wholesaler, and fish-hatchery manager.