Gravel Cleaner
First you need to set yourself up, you will need two water buckets, an old towel, a gravel washer (or a hose will do)
Using the hose hold the hose end in the aquarium and with your mouth suck the water from the other end until the water
comes out and then place the water in the bucket. This method takes a bit of practice though, sometimes the water does not flow or you may involuntarily swallow some aquarium water.
If you use a gravel washer the method is slightly easier. Keeping the end of the hose covered with your thumb. place the cylinder into the water and fill it with water. Lift the cylinder vertically out of the water and wait until the air has been released and the hose is full of water.
Place the gravel cleaner back in the aquarium and hold it on an angle (the cylynder is totally submergerd). Take your thumb off the hose end (near the bucket) and water should come straight out. Fill the first bucket up and then place the hose in the second. Throw the water in the first one out (uf you have plant use this water to feed them as it is a great fertilizer). Continue this process until you have removed 1/3 of your tanks water.