[header] How to replace a leaky aquarium [title] Clear the area. [step] You will need lots of floor space and an easy lift of the old tank. [title] Drain the tank, leaving about 10%-40% of the water, depending on number of fish and size of your tank and holding buckets. 
[step] For every 30 inches (760 mm) of fish no bigger than 7 inches (180 mm) you will need one 5 gallon (20 l) bucket. If this is not available, use anything that won't be too small or have harmful residue in it.