Common filter types

What is the best aquarium filter? Well that is all a matter of opinion. There are many kinds of filters out there that filter your aquarium water in different ways. One kind of filter you may like were as another person wouldn’t even use it if it was free. Also all filters have their pros and cons.

Before we hit the actual filters, we must understand some basics on what they are actually doing. What is the filter actually filtering? Well there are 3 main filter process:
Mechanical- the physical removing of particles and debris from the water in your aquarium
Biological- a housing for beneficial bacteria meant to effectively use the nitrogen cycle
Chemical- use of chemicals such as resins, carbon, or other synthetic material to remove bad chemicals from your aquarium water
Filters are not limited on only doing one of these functions. Some can do them all, others can do only one or two. Another note, oxygenation of the water is often a plus with these filters. Some are better than others.

Now the part you have been waiting for, the common types of filters out there:

Canister filters:
These filters are useful especially in large tanks. Within them you can place numerous kinds of floss, biomedia, carbon, resins, whatever your little heart desires. To that you can see how easily you can customize this kind of filter. The actual filter consist of a canister, which is a container that houses a pump and compartments for your media. Then their are tubes that are your inlet and outlet. This feature can let the filter be located in a cabinet and not hanging on the back of your tank. However some units like the magnum H.O.T allow a fishkeeper to keep a canister filter on the back of a tank much like a power filter would. The canister filter utilizes mechanical, biological and chemical capabilities.

Cons? Yup, I already said no filter is perfect. Canister filters are more pricey than others out there. Also it’s oxygenating capabilities are limited depending on how it is setup.

Under gravel filter (ugf):
These filters can be considered a double edge sword to many aquarist. This kind of filter is inside your tank, so nothing hangs on the back. An actual unit consist of a plate at the base the tank which gravel rest upon and uplift tubes were the outlets (inlets if running in reverse) is located. You can operate one of these either with powerheads or an airstone. Normal operation pulls water into the gravel. However you can run these in reverse via a powerhead and push water up through the gravel. Being that water flow is directed at the gravel this encourages beneficial bacteria to grow there. Also ugf filters are cheap compared to many other filters. The ugf utilizes biological filtration, but can offer some chemical filtration and good oxygenation when airstones are used.

Cons? Remember that double edge sword stuff? Well here it is. With all the water moving under the gravel, debris and particles tend to collect under the plate. If left there, nitrate problems can arise due to the debris rotting. Also plants and burrowing fish may cause issues with the operation of an ugf.

Sponge filter:
These filters are probably some of the cheapest you can buy. These consist of foam and utilize an airpump. How these work is that the air motion inside the foam cause a current so water enters the foam and exits with the air. Biological filtration is abundant here, however some mechanical filtration and good oxygenation is present. Chemical filtration is not usually associated with this kind of filter, however some carbon-embedded materials do offer some chemical filtration as well. These filters are ideal for small tanks and/or fry raising tanks.

Cons? Mechanical and chemical filtration is weak. There are other filters that can do more out there.

Fluidized filter:
These filters are similar to canister filters. However these are setup to create an ideal biological housing. The design is basically a canister filter however the compartment is filled with an inert media and usually has some sort of prefilter floss or sponge.

Cons? These filters don’t offer chemical or mechanical filtration. Also the cost of this filter is more than that of something a sponge filter can do.

Power filter:
These filters are very common. They come in two styles: Hang on Back (Hob, ho, or hot) and internal. Internal filters are on the inside of the tank which dampens motor vibrations thus are very quiet. Also they you don’t have to have anything hanging off the back of the tank. Hob models, the more common of the two work in the same way. Water flows into the unit via an inlet tube. there the water exits out by passing through a cartridge and falls back into the tank. Most cartridges offer all three types of filtration. Some contain a special cartridge solely for biological filtration. Other even allow a fishkeeper to customize the media he or she wants to put in the floss.

Cons? These filters are hard to hide and internal filters take up space in your aquarium. When the cartridge is depleted, most if not all of the biological filtration is removed. Also this kind of filter is not as easy to customize as are canister filters, most filter pads are floss and carbon. When the filter pad has become clogged, water bypasses the cartridge and flows back into the tank, which allows particles to re-enter the tank.

Not to be confused with an oxygen, calcium or some other reactor. These are not as common as the other filters. Reactors are much like a fluidized filter, but their media is specific. These house resins or other types of chemical filtration. Benefits are that you can control the specifics of a single type of media. This filter is design for chemical filtration only.

Cons? With the cost of these filters, a canister filter is more likely. There is very little customization if you want to keep it as a reactor only.

Diatomic filter:
These filters are also another type of filter not usually seen. The unit consist of a prescreened intake and a chamber for holding media. These can be hob or look much like a canister filter. These filters employ fine media to “polish” aquarium water of any fine particles. The results are a really clear water good in competitions. Also these filters are not too expensive. As you have it, these filters are more of a secondary mechanical filtration as they will clog easy.

Cons? As mentioned before, they clog easy so these should ideally be placed after a primary mechanical filtration. These filters again are hard to customize. They require a special media in order to be a diatomic filter. Also not many pet stores carry the proper media. Unless you specifically need crystal clear water, they aren’t needed.

Ultra-Violet (UV) Sterilizer:
This kind of filter doesn’t exactly employ one of the three types of filtration. However it does serve as a kind of filter. These kind of filter utilize a uv-bulb that is harmful to living tissue. As such they are encased in a thick plastic casing where no light escapes. The job of these filters is to kill algaes or floating organisms in an aquarium or even pond water. This clarifies aquarium water and helps prevent diseases among fish.

Cons? The bulbs should be replaced often, usually every 6 months, which these bulbs aren’t cheap. Also anything that can somehow make its way into the filter like fry will most likely be killed. These are specialized and best serve large aquariums or ponds that have a chronic problem that a uv-sterilizer will cure.

Plants as a filter? Yup, it’s true. Plants are colorful, they remove nitrates and oxygenate the water. Plants love them for cover or as food. A planted tank really adds character and a whole new personality to a tank. Out of the three filtration, chemical, specifically nitrogen removal is the main benefit. Uncommon, however some tanks may have plants as the sole filtration. Odd as it is this can work out especially if the tank has a low bioload and plant conditions are ideal.

Cons? Well these plants need to have the proper environment. In most cases this means proper lighting which most tanks don’t come stock with. The plants themselves require care and if they start to die, they will add to the nitrogen waste instead of removing it. If you don’t have luck with plants, then this kind of filtration won’t help you.

Bio Media:
This stuff includes resins, carbon, or inert substances. Most of the time you will find these in another filter, however these can be stand alone. For instance, bio-balls in a sump offer biological filtration. Using carbon much like gravel offers chemical filtration. Even putting floss on a pump intake to make a filter. You can use bio-media in just about any way you want. Depending on the type of media you use, these can provide all three kinds of filtration, but usually each kind is made for a specific kind of filtration.

Cons? Replacing bio-media to keep efficiency is a must. Floss will eventually clog or wear over time. Chemical media will saturate overtime. Biological filtrations clog and need to be rinsed or replaced. To effectively use bio-media, though has to be put in on how to utilize each type of bio-media (such as floss before biological media, so it doesn’t clog so fast).

Protein Skimmer:
This kind of filter is truely unique. It uses air to pull out nitrogen containing waste from water. This offers chemical filtration that doesn’t need to be recharged and oxygenates the water really well. A protein skimmer consist of a long reaction chamber in which water swirls around with air producing bubbles. Above is a collection cup that holds this foam. This foam is composed of dissolved organics that never have the chance of producing nitrates in your tank. Nothing really needs to be replaced.

Cons? Can their be any? Well I did say no filter is perfect. First of all, these filters only work in saltwater tanks. Next to be effective a good model is needed… A good model usually cost starting around $200. Also these kind of filters have a breaking period, so it takes a while to get started. Another con is the collection cup, these can overflow over time or if the foam gets produced too quickly due to another reason.

Well, did I help you any? Any last points? Ya, I have a couple. As you can see there are pros and cons to all filters out there, however you can minimizes the cons. You can employ several filters if you wish. Such as using an ugf with a power filter. The power filter would remove debris so less would be able to be trapped under the ugf. Also bacteria loss when you replace the power filter’s cartridge is minimized due to the benefits of an ugf. I’m sure there are other filter types and some that haven’t been invented yet. So as time goes on perhaps they will invent the “perfect filter”. Personally I like the power filter. I feel it offers enough filtration for most of my needs. However some other average Joe my swear by canister filters only. Point? Go with what you like best and what works best for you.

This article was written by: SerVo
You may print this article off in section and entirety and distribute freely. However you may not claim this article as yours in section and/or entirety because I wrote it, not you.