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AQUARIUM FILTRATION (Filters), Canister, HOB and Cleaning; how they work - by Carl Strohmeyer

There are several different kinds of aquarium filters, each with advantages and disadvantages. Most work best when used in combination to compliment each other, this redundancy is also important for peace of mind in case one filter fails, another will keep your aquarium filtering. I give my opinion too with each of these types of filters, based on 28 + years maintaining a Large Aquarium maintenance company in Los Angeles, California. I used many different types and brands of filters during this time, and continue to try new ones out.

Below I discuss the attributes (and weaknesses) of a few types of filters (HOB, Canister, Cleaning) and I give trouble shooting tips for each as well. Please see my full Aquarium Filtration article for MUCH more information about filters: "Aquarium Filtration."

Also as note, these articles are based on both facts and my opinions from using these filters under many different circumstances, so if I am somewhat critical of a certain filter, often it is just because of over blown hype around this filter, not that it does not necessarily work. I just do not believe in magic filters, conditioners, ECT that will do everything. For this reason even products I really believe in such as the Wonder Shell or Aquarium Cleaning Machine could use some renaming if it was up to me as the Wonder Shell is not a “Wonder” but a useful too and the Aquarium Cleaning Machine is not a “monthly maintenance miracle” but a very useful tool for proper husbandry.


HOB filters (hang on the back- power filters) are quite popular for good reason. They are generally inexpensive and simple to operate. These filters are good for mechanical and chemical filtration, but are generally poor for bio filtration. This does vary widely with the model though.

The Aqua Clear is better than most for biological filtration and is very popular for this reason among many experienced aquarists, but its design tend to lead to flow-by (see more about this later in this section), resulting in poor mechanical filtration especially for more fine debris (they also have poor impellers, and in my experience, have a higher than normal break down record and have a tendency to leak). Before I seem too hard on these filters (as I mentioned a lot of good aquarists do use Aqua Clears), these filters do have a lot of capacity and flexibility especially in the larger models (which is where I would recommend their purchase, the small Aqua Clears are really no better than any other HOB in terms of capacity than comparable Whispers, Via Aqua VitaLife
 ECT.). I do NOT buy the argument by supporters of Aqua Clears that the cartridge style filter is more expensive to operate and vastly less efficient biologically. With a pre-filter, the cartridges can last a long time (often a few months) and many come with grids or sponges to improve bio capacity.
The Aqua Clear Models I recommend are the 70 (old 300) and the 110 (old 500), these are useful filters in terms of capacity and versatility. The model 110 is a good choice for aquariums over 70 gallons especially if backed up by an internal filter.

One more point in favor of Aqua Clears (or at least the Model #70 and # 110), these can also be converted into a pretty good Nano Reef Filter with some live rock fragments (about 1”) or
volcanic rock
and even a small Mud Filter with the mud or even live sand in a fine nylon bag place in the bottom of the filter. Hopefully some of the impeller problems I have experienced in the past will (or are being) improved as the larger models of Aqua Clears are very versatile filters that I recommend (for smaller models, I still recommend Whisper, VitaLife or TetraTec).

The Penguin has good mechanical filtration (little flow-by), but are not as good for bio filtration, EVEN with the Bio-Wheel, which is vastly over-rated in my tests I preformed through my aquarium maintenance business. I removed the bio wheel on penguin filters on comparable aquariums with comparable bio loads and fish and found no discernable ammonia spike.
There are NO penguins I recommend, especially the Emperor models as I have had so many impeller problems with these not to mention they have the problem of becoming Nitrate factories.
For more information about my experiments with Bio Wheels, please read this article:
Do Bio Wheels really work?

The Whisper and Via Aqua VitaLife are the HOB filters I prefer the most for freshwater (although there are plenty of excellent aquarium power filters available). Both of these filters provide reasonable bio filtration with the bio grid or sponge. I give the nod to the VitaLife 200 though due to the surface skimmer feature (not to be confused with a protein Skimmer). These filters have a low “flow by rate” and are thus much better for mechanical filtration.
ReSun is a good economy HOB filter (very reliable and surprisingly powerful, but few features) and is less prone to leaks, but the ReSun currently has a poor choice of filter size options is currently only best for 15 gallon aquariums or less.

The newer
Via Aqua VitaLife HOB Filter has more features such as the bio grid for bio filtration and a unique surface skimmer (which a great feature!). This bio grid is a simpler and more reliable way to maintain nitrifying bacterial colonies than a bio wheel (The Millennium Filter also has this feature).
The even newer yet
HiQ Eco Power uses and excellent double cartridge system and grid that utilizes bio balls (one of the best bio HOB I have used to date, although the skimming feature of the Via Aqua is excellent too).
Before I seem like this is the style filter you should purchase, you need to look at what you need your filter for. If you have little debris in your aquarium but a high bio load, the Aqua Clear may be for you (their mechanical problems aside). As I will note in the next paragraph, a pre-filter will vastly improve this (although many Whispers come with a secondary sponge and the VitaLife has a bio-grid). With small economy HOB filters such as the ReSun or small Whispers a small rpalcement sponge
stuck into the filter next to the cartridge will help with bio filtration (for only $2).

In these style filters I prefer the ReSun for 10 gallon or less and often combined with a pre filter (for value reasons), the Via Aqua VitaLife M100
for 10-20 gallons or Via Aqua VitaLife M200 for 20-50 gallon aquariums, the Whisper 60 or Aquamaster 40 for 60-70 gallon aquariums, and the Aqua Clear 110 for over 70 gallon aquariums. Keep in mind that the previous opinions are subjective and your filtration needs may vary according to bio filtration vs. flow-by (mechanical filtration) needs and more.

Even though HOB Filters are not first choice for marine aquariums, they can and do work here as well, usually in smaller applications (under 60 gallons). I generally prefer the Aqua Clear or Via Aqua VitaLife M200
for this application, the Via Aqua being my first choice due to its surface skimmer feature (& price too!). For either filter the addition of Live Rock fragments or volcanic rock via a filter bag will improve marine aquarium filtration (I remove the bio grid in the M 200 and substitute the filter bag instead)

One more note about Whisper HOB filters; one nice thing about these filters is you can buy the “Bio Bag” filter inserts in bulk boxes cheaply at many local fish stores. I like this feature as it gives you options of economy and ease of carbon removal for treatment or established aquariums (which I rarely use carbon in except occasionally). You can “cut” the carbon out of Penguin, Vitalife, or other filters or simply let it become a bio media by not removing it and only rinsing the fiber part of the cartridge, thus saving money on new cartridges.

I performed a few tests on “flow by” on Aqua Clears vs. Whisper and a couple other HOB filters (for mechanical filtration and chemical filtration).
*Test [1]; Using a bare tanks (20 gallons) and original carbon. I added Methylene Blue and the Whisper removed the Methylene Blue quicker.

*Test [2]; I added a washed gravel slurry again to a bare 20 gallon aquarium and again the Whisper removed the debris much quicker this time than the Aqua Clear. I also have used the Penguin and Via Aqua Vita Life; both were also quicker at removing the debris as well (the Via Aqua was the fastest). During this test I used an air stone on the bottom to keep the debris suspended.
This experiment included these filers at the time it was conducted:
Aqua Clear 150 (now the #30), Whisper 2 (#40), Penguin 170 (replaced by 200), and Via Aqua Vita Life 200.


Popular filters for larger aquariums in particular, Canister filters are known for their large capacity (most canister filters with the exception of Magnums are the ‘Kings’ of capacity), which sometimes can be their problem. Many aquarists will not clean canister filters often enough as they are “still running well”, but in reality are have a large build up of organic sludge turning them into ‘nitrate factories”. I do recommend them if they are serviced regularly, as their ability to hold large amounts of different filter media and their excellent mechanical filtration set canister filters above most other filters. Canister filters are still one of the best choices for a filter for fresh water aquariums over 100 gallons, especially when well maintained with regular rinses in de-chlorinated water (including foam and ceramic media).

If used in marine aquariums I recommend the use of cured live rock crumbles or volcanic rock
to keep these filters from becoming nitrate factories. For more information about this, please refer to this article: Marine Aquarium Information

For MORE about filter media, please see this article: AQUARIUM FILTER MEDIA

Most Canister filters have a water flow that flow from the bottom (not the Magnum); in these filters I would start with coarse filter media at the bottom of the canister. I would use products such as Nirox Bio Care ceramic media for coarse filtration and bio filtration (rinse this with used tank water- never tap water!), then I would use a medium fiber or Ehfi-Fix, then I would use filter fiber or poly filter pads and place any chemical filter media between the fiber or even in a nylon bag. For soft water (Amazon River Aquaria), I recommend Nirox Bio Lif which softens water like peat, but also helps trap pathogenic bacteria such as aeromonas.

For quality and value I prefer the
Via Aqua (one of the most reliable I have ever used!) or Rena (API) Filstar (although a bit more money), the Eheim is excellent but way over priced for the questionably better quality (They sell more on hype in my opinion, this is not to say that they are not good filters, as they are). In fact their Wet/ Dry Model (2229 W/D) is not a true Wet/ Dry rather it purges water in and out of the canister, this produces a poor flow rate for larger aquariums in particular and tends to probe to problems.

The Magnum has unique convertible features (the ability to switch between standard canister filtration and micron), but their capacity is poor compared to the rest. Before one dismisses Magnums for their capacity, they have about the best head pressure as compared to comparable Canister filters which is especially useful for running UV Sterilizer, Fluidized filter, ECT.

Although popular, I am far less than impressed with the Fluval. They have weak motors, poorly designed impellers, and poor head pressure. I have had dozens of Fluvals on my maintenance route over the years, and their longevity is less than most others, even in the newer ’04 models (the ’05 models are too new to comment on as to longevity, however their design does not seem much improved to me). The Fluvals low head pressure, poor impeller, proprietary hoses, and more lead me to question why these vastly over rated filters are so popular, and I base this statement on years of use of these and other canister filters in REAL world applications.

Another often forgotten aspect of canister filters is that you can drill and use bulk heads to attach a canister filter. I have installed many canister filters from Magnum to Via Aqua 750 to Ehiem, often powering UV Sterilizers and/or Fluidized filters this way in MANY high end installations I have performed in my business. I also set up a whole fish department this way.
The over the top installation is more typical and works fine, however I have achieved better performance, and a MUCH cleaner look when drilled. When used this way your Canister filter is often easier to service (when valves are employed) and can more easily power additional equipment such as a UV Sterilizer, Fluidized filter, or Heater module.

For a diagram of a drilled aquarium application, please see this article:
Drilled Canister Filter Application


Cleaning Filters are devices used to both clean and filter aquariums and include the Diatom Filter (Vortex used to be a popular model), Aquarium water changers, and Filters such as the Aquarium Cleaning Machine . The Diatom filters use diatomaceous earth to filter water down to very fine micron size, and even filter out ich tomites. Often these filters are used in place of a water change, which they should not be. Also in my experience diatomaceous earth tends to strip some electrolytes from the water.
Personally I prefer the newer Aquarium Cleaning Machine
as this unit can first be used as a power vacuum to vacuum and drain water even up to a sink, then set to re-circulate through a micron & carbon cartridge where you can get the rest of the mulm out with out changing too much water. The micron cartridges in these can filter very fine particle including some parasites too.


This article just deals with 3 different filters, for more filters, pictures, troubleshooting and more, please see this article:
"Aquarium Filtration; how they work, disadvantages and advantages of each, DIY filters, troubleshooting and more"


Professional aquarium maintenance experience since 1978 as the owner of one of the larger aquarium maintenance companies in LA, CA.

I have been in the hobby since 1969.



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