Is It Possible to Overfill an Aquarium?

Fish tanks are generally acquired by their volume. For example, 20-gallon tanks are often sold as part of starter freshwater aquarium kits for beginners, and their shapes are rectangular for the most part. The volume capacity of a fish tank gives you an idea about how heavy it can be once it’s filled with water, substrate, decorations, and aquatic species. In the case of 20-gallon tanks, we’re talking about approximately 225 pounds, which means you would have to provide furniture or a structure to support such weight. The volume measurement refers to the tank filled to the very top, but you should never fill it up so much.

Recommended Aquarium Water Levels

In the fish keeping world, you should always work with as much water as possible. You’ve probably heard about the dangers of having a bioload that’s too high for the water volume, but this shouldn’t prompt you to fill the tank all the way to the top, which would be considered overfilling. Modern aquariums come with synthetic edge trimming at the top for the purpose of accommodating lids, lamps, and automatic feeders. These trim pieces measure between 1.5 and 2 inches, and they’re a good reminder of an ideal water level. In fact, you may want to only fill the tank to an inch below the trimming for reasons explained below. This also goes for the newer style of “rimless” aquariums.

Leaving Enough Space for Adequate Gaseous Exchange

The mechanical aeration of the water column is the main source of oxygenation in an aquarium, but this requires a natural exchange of carbon dioxide and oxygen. The water surface needs to be agitated for this to happen, but there needs to be sufficient space between the aquarium walls to promote the exchange, which is why the water should stop about an inch below the trimming.

The Importance of Keeping All Species Submerged

Littoral aquariums and terrariums are two kinds of specialty tanks that are typically filled at the halfway point because some species, particularly plants, don’t need to be submerged. Unless your exotic aquarium fits this description, you should always fill the tank with enough water for rooted plants to grow vertically until they reach heights of about an inch below the trimming. At the same time, you should keep plants trimmed so they don’t break the waterline.

Keeping Water Inside the Tank

A powerful aeration system is always desired, but such a system will increase the likelihood of water splashing above the surface, over the top of the tank, and onto the aquarium stand or even the floor. Aquarium lids can minimize splashing, but not if they’re the porous kind, which are always preferred because they facilitate the aforementioned gaseous exchange.

Maintaining the proper water level is just one of the many tasks involved in caring for an aquarium. You’ll also need several important supplies. At Aquatic Warehouse, we carry everything you’ll need when it comes to freshwater and saltwater aquarium supplies. Stop by our store in Kearny Mesa, order what you need from our website, or give us a call today at 858-467-9297 if you have any questions.