Assemble as per package directions, attach end of airline tubing, then place in rear corner of aquarium. Allow remainder of airline to simply hang out the back of aquarium for now.

Special note: many colored or other packaged varieties of gravel are quite clean, and do not require washing. Put a few tablespoons in a glass of water to test. If the water remains clear, skip this step. Place a few inches of gravel in a clean, soap-free bucket and fill with water. Stir gravel thoroughly, then pour off water. Repeat until rinse water is clear. Never use soaps or detergents on anything that goes inside an aquarium.

Pour gravel into aquarium, covering sponge filter, then go back to rinse the next batch. Continue until there is 2" to 3" of gravel in the tank.