Within the larger aquarium hobby, saltwater aquariums are often attached to various misconceptions that ultimately create hesitation for hobbyists looking to transition from a freshwater aquarium into saltwater.  

  • Saltwater tanks are hard
  • Saltwater tanks are expensive
  • The fish and corals are too fragile 
  • The equipment is too complicated and pricey
  • I don't want to buy new equipment just to accommodate saltwater fish.

While much of this is subjective and many will disagree about the accuracy of these statements, the truth is this hobby can be as complicated or as simple as you want it to be. You don't need to buy all new gear, your freshwater aquarium and filtration will work fine. The necessary maintenance is almost identical to a freshwater aquarium. There are affordable and hardy saltwater fish and you can find success with a relatively simple filtration system. 

When it comes to the filtration system specifically, what you're using on your freshwater tank will probably work just fine but there are additional pieces of equipment and techniques, specific to saltwater aquariums, that could be employed to help you succeed.  

What is the difference between a saltwater and freshwater aquarium filtration system?

This just depends and it is best answered with specific information about common pieces of equipment.  At the core of it, all filtration systems are performing the exact same function  - exporting nutrients and maintaining suitable water quality for the animals in your care. How you go about doing that will be specific to you and your aquarium.  

Submersible, Canister, and Power Hang-On Filtration

These are the most common types of filtration for a freshwater aquarium and all three of these will work great on a basic saltwater aquarium. If making the transition from freshwater to saltwater, simply clean the equipment thoroughly and get brand new media to use on your saltwater tank. 


Sumps can be used for freshwater aquariums but are more commonly used in saltwater aquariums, at least when it comes to home aquariums.  A sump is simply a remote container that is connected via plumbing to your display aquarium which creates room for additional or more complex filtration equipment. A sump makes it easy to hide equipment out of plain view and in many situations is easier to access and maintain. A sump also increases the total system water volume which is a benefit because it's easier to maintain stability in larger volumes of water. 

Protein Skimmers

Protein skimmers are specific to saltwater aquariums. They use a process called "foam fractionization" which doesn't really work in a freshwater environment.  The process involves creating a dense foam that is baffled and channeled in such a way that allows you to remove concentrated waste. Protein skimmers are highly effective and have become commonplace in saltwater aquariums. As an added benefit, the dense foam promotes a considerable amount of gas exchange keeping your water oxygenated. Most skimmers are used inside of a sump but there are submersible and hang-on style protein skimmers that work just as well. 

Algal Filtration - Refugiums, Scrubbers, and Reactors

This is another technique specific to marine aquariums and engages algae as a means of nutrient export. The idea is simple and highly effective - as algae grow they will consume nutrients and by controlling the growth of algae inside some kind of vessel, you can easily harvest that algae and you will effectively be removing all of the nutrients it has consumed. It's natural, does not require any kind of media, and can be maintained with relatively minimal maintenance. There is also the added benefit of CO2 consumption which helps maintain stable pH levels. 

To wrap this up into a single sentence would be a disservice and ultimately your filtration system often grows and becomes more complex relative to your maturity in the hobby. This holds true for both freshwater and saltwater aquariums in many cases. Maintaining a simple fish-only saltwater aquarium can be done with a glass box, heater, and power hang-on filter - exactly like that you would use on a freshwater tropical community aquarium.  Maintaining a marine reef aquarium is more complex with specific gear tailored to corals and invertebrates, just like a freshwater planted aquarium requires CO2 and more complex gear to accommodate the plants. 

So the basic answer is NO, you don't need a special filter for a saltwater tank, especially when first starting out. You do, however, need to choose the right tool for the job and understand the filtration system may evolve over time based on your particular goals and desires for certain livestock.