It starts out slowly. The first day you get your fish, your tank is sparkling clean. A few weeks later you notice the tank is looking a little cloudy. You ignore it. Two more weeks go by and your fish tank is starting to look like mine did. This can be very overwhelming for a new fish owner. Don't sweat it, I've got you covered. Just follow this step-by-step instructable, and before your fish know what's happened they'll have a fresh, clean tank.
Step 1: Background
Before beginning the tank cleaning process it's important to note a few things first. This instructable is designed for small to medium sized tanks (5-20 gallons). The instructable is also designed for freshwater tropical fish, meaning that the water temperature is meant to stay in the mid 70's. The tank that I am demonstrating on is a rare case. It is much dirtier than it should ever be. Most cleanings should not wait until the tank is this dirty. In fact, every other week you should plan on cleaning your tank.
Step 2: Materials
Temporary fish tank.
Large bucket for waste water.
Step 3: Unplug Electrical Devices
The first thing you will need to do is unplug all devices such as the aerator, filter, and heater. I suggest leaving the hood lights plugged in and simply setting the hood behind the tank to help illuminate the tank.
Step 4: Remove Decor & Fish
Begin removing all decorations and electrical devices from the tank. Be carefully not to harm the fish in doing so. Once the decor is removed, you can next remove the fish. Fill your temporary fish tank with some of the original fish tank water. It is important to use the current tank water when filling the temporary tank as this will provide less environmental stress on the fish. Gently transfer all fish from the current tank to the temporary tank using the fish net. Be careful not to allow the fish to jump from the temporary tank. I recommend having a lid cover the temporary tank.