- 1). Turn off the filters and pumps. You may leave aeration devices running, or turn them off to improve visibility.
- 2). Remove plants, rocks, decorations or animals that may be in the way or may get sucked into the siphon. Place them in a holding tank filled with water from the aquarium from which they came, preferably with an aerator.
- 3). Set a net on top of a bucket. You will place one end of the siphon in the net to catch the gravel as it comes out of the siphon. The bucket will catch the dirty water.
- 4). Start your siphon. For this, the manual sort of siphon that does not attach to a sink faucet works best, and you can begin the flow by gently sucking on the end of the siphon and letting gravity do the rest. The siphon must be powerful enough to suck up gravel. Be careful of fish, plants, coral, etc.
- 5). Move the siphon along the gravel, allowing it to suck up the gravel and any debris or waste. Do not remove more than 30 percent of the total water volume at one time.
- 6). Repeat step 5 in another week if you are unable to get all the gravel out at once without draining your tank.
- 7). Replace water and add the substrate. Allow the filtration system to run and debris to settle before returning fish or coral to the tank.
- 8). Save or discard the old gravel and dump the bucket of dirty water.
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