Pruning plants and cleaning debris
55 Gallon Fish Tank cleanings are the perfect time to prune your aquarium plants. Remove and discard any dead or dying plants and gently stir up the substrate. This process will allow the debris to settle on top of the gravel making it easier to remove.
The next step in the process is to remove the debris from the gravel and siphon off about one third of the aquarium water. There are siphons that you can purchase, which will remove the debris and water without removing the gravel. Siphon the water into a large bucket and if you happen to have houseplants, use this water on them. Aquarium water is a good nutritional source for houseplants.
Cleaning filters in 55 Gallon Fish Tank
As per http://www.myaquarium.net/55-gallon-aquarium-kits-and-fish-tanks-compared/, You will need to change your filters and replace the siphon water with fresh water. If the filters require rinsing, be sure to do it in the removed aquarium water, not fresh tap. Using tap water will disturb the good bacteria in the filter. Mix the water and salt product outside of the aquarium in a bucket that is only used for the aquarium. Fish are very sensitive, and traces household chemicals left in a cleaning bucket can poison in your tank.
If you are using tap water to fill your aquarium, be sure to remove the chlorine from the water prior to adding it to your tank. Adding drops to the tank after you have filled it with chlorine is like closing the barn door after the horses have left. Chlorine has a negative effect on your fish and their environment from the moment it enters your tank, be sure to remove it first. Check the temperature of the water being added to the tank to be sure it is within two degrees of the water temperature inside the aquarium.
A word of caution! If you clean the outside of your tank, be careful not to introduce chemicals to the tank. Products like Windex can be the kiss of death for 55 Gallon Fish Tank. Remember, ammonia is toxic to fish, and Windex is ammonia-based. White vinegar is a safer option when cleaning the outer glass of your aquarium.