I have a large 150-gallon freshwater aquarium. I know that sumps are popular in the marine aquarium hobby, but are they needed for freshwater aquariums?
Sumps are used in the marine aquarium hobby for several reasons. Some people use sumps to increase the total water volume of their aquarium, making it easy to maintain salinity levels and dilute waste. Others use sumps to house refugiums or the plethora of equipment needed to run a large reef. Because you wouldn’t be balancing salinity in a freshwater aquarium or need large filtration items like protein skimmers or calcium reactors, it’s hard to imagine that a freshwater system would need a sump. It could be an over-the-top expense and headache for a freshwater aquarium – but let’s take a look at the options a sump could add to a freshwater aquarium.
First, a sump would increase the amount of water available for the total aquarium system, thus diluting dissolved organics in the water. It could open up options for the aquarist in terms of filtration. For example, a canister filter could be plumbed into the sump, freeing up the back wall of the aquarium and creating less of an eyesore. It would also allow the aquarist to easily incorporate a UV sterilizer. Sumps work well for water changes and act as an easy place to dose an aquarium with any needed maintenance chemicals. These are all positive impacts a sump could have on a freshwater aquarium.
Also a sump could be used as a temporary holding facility (post quarantine), for new fish. Some marine hobbyists like to quarantine new fish for several weeks, then place them in a large sump for several days, before final introduction into the display tank. This serves two purposes in that it allows the new fish to comfortably adjust to the display tank’s water without being picked on and it gives the aquarist a chance to observe the feeding habits of the new fish in closed and easily monitored quarters. I would assume this same technique could easily be applied to freshwater aquariums that contained a sump.
As I think about it, I can find many advantages to having a sump on a freshwater aquarium and not many disadvantages. Once set up with a proper overflow, sumps are easily managed and if you have the additional room needed, it would only enhance your current aquarium’s potential. While a sump may not be totally necessary for your aquarium, it may be a fun project to attempt, and discovering all the potential uses would be interesting and could even benefit your fellow aquarists.
When we consider that old aquariums can easily be converted into sumps or that glass sumps can be cheaply built, it becomes a more encouraging proposal. Because you may not need the flexibility or size that many large acrylic sumps provide, creating your own unit for a freshwater tank could be fun and cost-effective.