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Aquarium Power Filters (HOB Filters) - by Carl Strohmeyer


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, 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, 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.

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. Yet when HOB filters that had running pre filters attached to their intakes were removed, there were discernable ammonia spikes.
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.

The Whisper, VitaLife and ReSun (a basic very reliable filter) the HOB filters (and many similar) I prefer the most (although there are plenty of excellent aquarium power filters available). These filters have a low “flow by rate” and are thus much better for mechanical filtration... The 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. The newer Via Aqua VitaLife HOB Filter has more features such as the bio grid for bio filtration and a unique surface skimmer. 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). 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 Replacement 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 15 gallon or less (for value reasons), the Via Aqua VitaLife 200 for 30-50 gallon aquariums, the Whisper 60 or Aquamaster 40 for 60-70 gallon aquariums.

This brings me to the point that many HOB filters can or should be equipped with Pre Filters (the
Filter Max is the best due to its patented sponge technology). Pre Filters vastly increase bio filtration, are inexpensive ($4.99 and up), prevent baby fish from being sucked into the filter, and provide a measure of bio stability when the cartridge is changed. It should be noted that with Aqua Clears, pre filters are not as necessary for bio filtration (they still improve it though), although they still prevent fry from being sucked into the Aqua Clear.
A complaint with pre filters I have heard (not experienced) is that they end up performing all the mechanical filtration duties of your HOB filter; this is not true. With cartridge style HOB filters (Penguin, Whisper, Via Aqua, ECT.), the pre-filter will remove most of the medium to coarse debris BEFORE passing into the cartridge where the cartridge will then remove the more fine debris. This will have the added benefit will be longer periods between cartridges which will also save you money.

Potential HOB Filter problems:

Make sure to clean the impeller regularly, also clean the area the impeller “nests” to prevent debris from stopping the impeller. If the impeller stops, check for carbon caught in this area and make sure impeller itself is not broken. The impeller should be to turn 359 degrees before locking, if the impeller spins freely or not at all, it is broken.
Clean filter intakes with a foxtail brush to prevent build up that will slow the filter (a sponge pre-filter helps prevent this).

For bio wheels, make sure the Teflon ends on the bio wheel axle are clean and have no build ups of calcium, you can replace these with Teflon tape in a pinch. Also make sure the bio wheel assembly is not to tight, simply remove the bio wheel and gently stretch the assembly apart so the wheel can spin more freely.

HOB filters are good compliments to sponge filters or under gravel filters.

For my FULL Aquarium Filtration and Filters article with information about many more types of aquarium filters and pictures, please visit this link:



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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