I'd like to get dressed up and have a tea party inside a fish tank. In order to do such a thing, I must make sure the tank is clean and free of fish poo. Here are the steps one needs to take to do such a thing: Make sure you have everything you need! Run through your checklist, and make sure everything you need is within reach.
Start the siphon and direct the water into a 5-gallon pail. You may need a larger bucket if you have a large aquarium.
Push the gravel vacuum through your gravel. Fish waste, excess food, and other debris will be sucked out through the vacuum.
If you have a sand substrate, do not use the vacuum like a shovel. Use just the hose part of the siphon, not the plastic tube, holding it under an inch from the surface to suck up waste without disturbing your sand.
If your decorations are covered in algae, you may want to feed your fish less or change the water more frequently. Excess algae growth is caused by excess nutrients in the water. You can wipe the decorations off in the tank water you siphoned out, and use an algae scrubber to remove algae from the walls of the tank.
Don't change the filter cartridge unless it is falling apart. The filter is where a lot of the beneficial bacteria in your tank lives, and replacing the cartridge will kill the bacteria and cause toxins to build up in your tank. Instead, you can rinse it in the old tank water to clean it off every once in a while.
Replace the water you took out with fresh, treated water at the temp of the aquarium.
Any cloudiness that remains will normally dissipate in a few hours, leaving the water sparkling clear.