Guide · Water changes and testing
How to prime a gravel vacuum
Three ways to start a siphon gravel vacuum without mouth-siphoning: the up-and-down shake, the submerge-and-lift method, and a faucet water changer.
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Short answer
Put the bucket well below the tank, put the vacuum tube in the water, and move it quickly up and down until water flows over the top of the tube and down the hose. Aqueon says that is how its siphon vacuums are primed. If shaking does not work, fill the whole vacuum underwater, pinch the hose end shut and lower it into the bucket. Either way, no mouth-siphoning is needed.
Before you start
A siphon only runs downhill, so set up for it:
- Bucket below the tank. The lower the bucket, the stronger the flow. The floor is usually fine.
- Hose free of kinks and long enough to reach the bucket.
- Tube near the bottom of the tank, but not yet in the gravel.
- A towel under the bucket and the hose end.
Method 1: the up-and-down shake
Aqueon says its siphon gravel vacuums are primed by moving the intake tube up and down.[1]
- Hold the hose end in the bucket.
- Put the tube in the tank, open end down.
- Move it quickly up and down a few times. Water climbs the tube a little with each stroke.
- When water spills over into the hose and starts running to the bucket, stop shaking and hold the tube steady.
If it stops, lift the tube out of the water for a moment and start again.
Method 2: submerge and lift
- Lay the whole vacuum, tube and hose, in the tank so it fills completely with water.
- Pinch the hose end shut, or cover it with your thumb.
- Keeping the tube under water, lift the hose end out over the rim and down to the bucket.
- Release. Water flows as long as the bucket end is lower than the tank.
This works with any siphon vacuum. Wash your hands afterward.
Method 3: skip the siphon
A faucet water changer drains to the sink and refills from the faucet, so there is no siphon to start and no bucket to carry. See the faucet water changer guide.
Vacuuming once it runs
- Push the tube into the gravel, let the waste lift, then pull it out before the gravel rises too far, and move to the next patch.
- Watch the water level, not just the gravel. Stop when you have removed the amount you planned to change.
- Refill with treated water. Merck says new water should be dechlorinated.[2]
How often: Merck's general schedule is a water change every two weeks, with the amount depending on stocking, and it describes using a water and vacuum system to remove waste from the gravel during the change.[3][2] Python, a maker of water changers, recommends 5 to 10% every other week for its users.[4]
Pick a size for your tank
Aqueon sells siphon vacuums from a mini 5-inch tube up to a large 16-inch tube. It lists the mini, with a 6 ft hose, for 1-5 gallon aquariums.[1] A tube that is too long for a small tank is awkward to use; one that is too short for a deep tank puts your hand in the water.
When it will not start
| Problem | Fix |
|---|---|
| Water rises in the tube but will not go down the hose | Lower the bucket; shake faster and longer |
| Flow starts, then stops | Air leak or tube lifted out of the water; keep the tube submerged |
| Flow is weak | Bucket too high or hose kinked |
| Gravel goes up the hose | Pull the tube out of the gravel sooner, or pinch the hose to slow the flow |
Next
Questions
Why won't my gravel vacuum start siphoning?
Usually the bucket end is not low enough, there is air in the hose, or the tube is not deep enough in the water. Keep the bucket well below the tank, fill the tube completely and try again.
How do you start a siphon without sucking on the hose?
Aqueon says its siphon vacuums are primed by moving the intake tube up and down in the tank. You can also submerge the whole vacuum to fill it with water, block the hose end, and lower it into the bucket.[1]
What size gravel vacuum do I need?
Match it to the tank. Aqueon sells sizes from a mini 5-inch tube to a large 16-inch tube, and lists the mini, with its 6 ft hose, for 1-5 gallon aquariums.[1]