Should You Vacuum Your Aquarium Gravel?

Vacuuming an Aquarium

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Your aquarium's maintenance needs can vary based on your setup, equipment, and time. Along with installing the proper filtration systems to maintain water quality, it's also important to clean the gravel at the bottom of your tank to keep conditions healthy for your fish. The simplest way to carry out this procedure is by using a gravel cleaner, or gravel siphon.

What Is a Gravel Cleaner for Fish Tanks?

An aquarium gravel siphon is a manually operated vacuum that pulls gravel up from the bottom of the tank, then churns it in water to remove dirt, algae, and fish waste.

There is some debate as to whether this procedure is necessary and if it could possibly be making your water quality worse. No matter your setup, vacuuming makes your tank a healthier environment for your fish.

What Is "Vacuuming?"

If this is a foreign concept for you, don't worry; you are not alone. Vacuuming an aquarium is performed using a gravel siphon. This siphon is made up of a large, rigid tube connected to narrower, flexible aquarium tubing. There are some that will hook up to a sink to assist with siphoning; otherwise, you will need the assistance of gravity.

Some vacuums come with an air-filled bladder to start the pull of gravity. Others you will need to start the siphon manually. It is not recommended to suck on the open end of the siphon! Although rare, there are a few zoonotic diseases you can catch from your fish, not to mention getting water in your lungs.

Once your siphon is started, vacuuming is a simple process. If your substrate is too deep (more than two inches), vacuuming may not be sufficient to clean the deep layers. Stick the rigid tube into the substrate and allow a few seconds for the sand/gravel/rocks to be pulled into the tube. Before they get more than halfway to three quarters into the siphon, pick up the tube and allow the substrate to fall back down. You will see the lighter particulates, mostly fish/plant waste and excess food, floating up the siphon and into the flexible tubing. Repeat throughout your substrate.

What Does "Vacuuming" Do?

Vacuuming removes the small particulates from the substrate. Mostly, this is made up of fish waste, dead plant material, and excess food, especially if you feed a flake diet. These lighter particulates get sucked away while your substrate stays in place.

If those particulates were left in place, it will cause problems with your water quality. Leftover food, fish, and plant waste break down and release ammonia into your water. Ammonia is toxic to fish and why you work so hard to cultivate good bacteria in your biological filters. By removing these particulates before they break down, you will decrease the ammonia concentration in your aquarium.

Deep pockets of debris, once cut off from oxygen in the water, can develop anaerobic bacteria populations. These bacteria use sulfur as a food source, and when disturbed, release hydrogen sulfide into the water. This is another toxic substance that can kill fish and cause increased disease. You will know if you have accidentally disturbed these bacteria since your tank will smell like rotting eggs. If this happens, evacuate your fish to clean, treated water as soon as possible, and thoroughly rinse your aquarium before putting your fish back.

But If I Vacuum, I'll Remove The Good Bacteria

The particulates you vacuum up are small but not microscopic. Your good bacteria live in your substrate deep within the crevices. Vacuuming will remove only a tiny percentage. If you are relying on your substrate to do the bulk of your biological filtration for your nitrogen cycle, your system is not sustainable.

All tanks must have biological filter media to colonize good bacteria. Be they sponges, matting, fluidized beds, socks, bioballs, or rocks, there are many ways to house good bacteria in fish tanks. Vacuuming your substrate as part of your regular maintenance will not significantly diminish your bacterial colonies.

What About Planted Tanks?

These systems may be less well tolerant of vacuuming. Plant roots can become dense and make vacuuming almost impossible. For these systems, it is critical that the roots get oxygen. It is recommended you use a substrate specific for plants.

What if I Don't Have a Vacuum?

If you do not have a vacuum, you must have another way of removing fish waste and plant material from your tank. Undergravel filters are a tricky business and should not be used as a complete maintenance replacement. In fish tanks with only a few fish, some owners remove waste with a simple turkey baster. Scavenger species, such as shrimp and snails, can break down the waste organically, but only in tanks with low fish density.

You must also be very careful when feeding to make sure there is no excess food wasted. This is easier when using a pelleted food over a flake food. Pelleted foods pack more nutrition overall and come in very small sizes.

How Often Should I Vacuum My Tank?

As with all the best maintenance routines, regular vacuuming, either once a week or once every other week, is best for your aquarium. Be sure to remove all your decor prior to vacuuming. You'll be amazed how much waste settles under those pretty plants and castles.

Vacuuming provides a quick and easy way to perform your regular water changes. Use the waste water for your plants or gardens!

Overall, vacuuming is an easy way to keep your aquarium healthy and will not decrease your biological filtration.

Article Sources
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  1. Estuarine Aquarium Keeping for Beginners. Chesapeake Bay National Estuarine Research Reserve.

  2. Zoonoses Associated With Fish. Washington State University Institutional Animal Care And Use Committee.