How to Use a Gravel Vacuum to Clean your Fish Tank or Aquarium

Unless you keep a bare-bottomed tank, cleaning the substrate in your aquarium is one of the many essential maintenance jobs all fish keepers much perform.

But, if you’re new to the hobby, figuring out how to work a gravel vacuum (also known as a siphon) can seem baffling.

How to use a gravel vacuum, written beside a bright yellow fish foraging through gravel.

Comprised of just a plastic cylinder and a flexible hose or tube, it doesn’t look like it could vacuum much of anything. However, once you get the hang of using it, you’d be surprised at how effective it is.

Want to make sure your aquarium is as clean as can be? Read on to learn the mysteries of how to use a gravel vacuum.

Why Do You Need to Vacuum Your Gravel?

Plainly put, vacuuming the substrate in your aquarium regularly is just good cleaning practice.

Debris, such as fish waste and uneaten food, can accumulate deep in the gravel. If left to rot indefinitely, bad bacteria may form, which could be harmful to your fish.

How Often Should You Do it?

Want to know how often you should use a vacuum? Well, even among experts you’ll find more answers than there are minutes in the day.

Some people say you should vacuum your substrate at least once a month, some say weekly, others even with every water change.

Others believe vacuuming your gravel too often isn’t beneficial when you’re trying to cycle your tank, as it doesn’t allow good bacteria to build up. People with this opinion generally advise siphoning no more than once every six months.

What we’d suggest is finding a routine that works for you, based on how well-stocked your tank is and how much waste tends to accumulate at the bottom of the tank.

How to Use a Gravel Vacuum: Step by Step

Now, let’s get down to the nitty-gritty method of how to use a gravel siphon to vacuum the debris out of your fish tank.

  1. Collect your equipment. You’ll need a siphon with tubing attached and a large bucket.
  2. Position your bucket. The bucket should be lower than your fish tank (on the floor, for example).
  3. Fill the siphon. Submerge the siphon in the water of your tank to fill it up.
  4. Create a vacuum. With your thumb or finger over the end of the siphon tube to stop any water coming out, lift the siphon out of the water and hold it up vertically. Water will start filtering down the tube, pushing air out. Once all the air’s been pushed out, release your thumb or finger from the end of the siphon tube (which should be in the bucket) and let the water start to drain out. This creates a vacuum.
  5. Put the siphon back in the tank. Before all the water has drained out of the siphon, submerge it back into your aquarium.
  6. Start vacuuming. Dig the head of the siphon down into the gravel. You’ll notice that it starts sucking the gravel upwards, along with dirty water and debris. You don’t want tit to go up into the siphon tube, but you do want it to suck up as much of the debris as possible and move the water down into the waiting bucket.
  7. Keep vacuuming. Repeat step six until you’ve vacuumed all, or at least most of, the bottom of your tank.
  8. Empty the bucket. You don’t need that dirty water, so empty it down the drain. You may find you need to stop and empty the bucket a few times during the process, depending on the size of your tank. If so, you’ll need to repeat steps three to five to get the vacuum started again.
  9. Refill your tank. Because the siphon sucks up water, as well as dirt and debris, you’ll need to top up your aquarium once you’re done. However, be careful not to empty out more than 25 percent of the water in the tank in one cleaning session. Refill your aquarium with suitably treated/dechlorinated water.

You might also be interested in:

Alternative Starting Methods

Above, we’ve explained how to start the most basic kind of gravel vac, with no self-priming features. However, if you splash out for a more expensive option, you may find that it’s easier to start.

Some models have a flow control valve. In which case, you merely have to submerge the business end of the vacuum and shake it in an up and down motion a few times to get it started.

Another type of gravel vacuum features a priming ball, which sits at one end of the siphon tube. With the siphon fully submerged and your finger blocking the end of the tube, squeeze the priming ball until water reaches over the lip of the tank, then release your finger from the end of the tube, and the suction should start.

Video: How to Siphon Your Fish Tank

If you’ve read our step by step guide, but still aren’t 100 percent clear on the details, this video will show you exactly what to do.



So now you know how to use a gravel vacuum. Simple, effective, and hopefully you can now see the benefits and just how easy it is to work into your fish tank maintenance routines.

Siphoning regularly keeps your fish’s environment clean, their water parameters more stable, and the whole ecosystem of your aquarium healthier.

Another bonus not to be overlooked, is it also extends the time between you having to do deep cleans, by preventing the build-up of uneaten food and fish waste that gets buried at the bottom of your tank.

The siphoning action of an aquarium gravel cleaner is also a great way to empty water from your tank for partial water changes. So each time you use the siphon, not only are you removing large pieces of waste, but you are also removing polluted water and replacing it with fresh.

A siphon is a great tool, easy to use, highly beneficial and we cannot recommend the regular use of one strongly enough.

Happy fish keeping!

B Hamilton

Hey there! I'm Brian, a lifelong enthusiast and fish keeper with a wealth of knowledge and experience on freshwater aquariums, that I love to share on this site. If you have any questions or need any help, please do ask in the comments section below, I'd love to hear from you and will help where I can.

Leave a Comment