In the endless search to find the best filtration setups, you may have come across a particular type of external drip filter known as a wet/dry filter. If you’ve never seen one before, I’m referring to those big, clear, square filters with the long tube and sump/pump setup.
No doubt you wondered how they work and how they compare to the ever popular canister filters, right? I’ve wondered the same thing and thought a quick comparison between the two would be helpful so you can see if they might be a good option to add to your aquarium setup.
Comparison canister filter Vs Wet / Dry Filter
| canister filter | Wet/dry filter |
|---|---|
 |
 |
|
|
Design / operation
They are both external filters, but the design of each is different and the internal workings are also different in some respects. In general, wet/dry filters are larger than cartridge filters. They are rectangular and, depending on their capacity, will have several subsections where the filter media is retained and the water enters the filter.
Using a device known as an overflow, the water flows out of the tank and is drawn into the filter through a gravity drain pipe. Depending on the size of the filter, this can be a single inlet pipe or a double inlet. The dirty water from your aquarium then passes through the biological filtration media contained within the «tower portion» of the filter. Mechanical filtration, if included, is often located in the filter drip pan.
After filtration, the water collected in this reservoir (also called sump), is sent back to the tank through a pump located at the bottom of the filter. Unfortunately, many wet/dry filters do not include the pump and you will have to purchase it separately, making sure the maximum pumping power of the unit you purchase matches the maximum pumping capacity of the filter you already purchased.
The smaller canister filter, on the other hand, is tall and cylindrical and comes with everything you need to get started. The internal pump draws water from your aquarium; Pressurized water is forced through the filters internal media pans or media chamber, and the filtered water is returned to the tank through an outlet tube.
Performance
Wet/dry filters shine when it comes to biological filtration, as their focus is directed almost exclusively at it. They have a large biofiltration media storage capacity, which can reach over 10 gallons if you get the right model.
Regarding the internal capacity, they can vary, but go up to 35 gallons in some of the larger models. Their flow rates and recommended tank sizes can also get quite high, up to 300 gallons at 1,200 GPH.
The drawbacks? In the first place, the level of mechanical and chemical filtration is practically nil. They sometimes have cartridges for chemical and mechanical filtration, but they are not as effective as what you get with a good cartridge filter. If you choose a wet/dry filter for your tank, you will need to supplement with another filter for additional wet cleaning methods.
Using a wet/dry filter increases the amount of tank water that is lost to evaporation. Additionally, wet/dry filters almost always have higher initial start-up costs (which are further increased by the need to purchase a separate pump).
Canister filters, by comparison, provide higher than average levels of all types of filtration and are especially effective when it comes to mechanical and chemical filtration. They offer a wider range of media that can be used in conjunction with the filter.
Although peak flow rates and capacities aren’t as high as wet/dry filters, they still pack a punch, with models like the sunsun Pro filter kit and the superior fluval fx6 topping out at 400 gallons at 925 GPH.
Canister filters can also come with additional features like anti-clogging filters, multi-directional outlets, and UV sanitizers to help control algae growth and promote even healthier tank water.
Installation / Maintenance
Both models require a bit of work to get up and running, although the installation process on the canister filter is generally more involved. It requires one to fit several components together, measure and cut the pipe, cut and install mechanical filtration media, prime the unit, etc.
Most wet/dry filters, on the other hand, only require one to install media, set up the overflow box, insert a pump, and connect any necessary hoses. All easy steps.
Canister filters also require a bit more maintenance. It needs to be disassembled to wash the parts and media separately on a regular basis. Wet/dry filters also need regular cleaning, but typically, they only require you to remove dirt from the filter media and tubing.
The verdict
Both filter styles are very powerful, but while wet/dry filters have the admirable distinction of providing the best biological filtration, they lack in several key areas of canister filters.
Wet-dry filters do not provide the level of mechanical or chemical filtration that many tank owners desire and require a more significant initial investment due to the need to purchase a separate pump to make them functional.
Contrast cartridge filters. They may take a bit longer to set up and don’t provide the same level of biological filtration, but they are by no means disastrous in this regard. Plus, they provide exceptional chemical and mechanical filtration, are highly customizable, and typically come with everything you need to get up and running.
If you’re the type that enjoys easy maintenance, there are canister filters available that take much of the hassle out of the traditional process of lugging large cameras to the sink. The Fluval FX6, for example, features a purge valve and smart pump technology that helps with water changes and maintenance of the various filter components.
