3 or 4 5 gallon buckets. net out the fish etc into 1 bucket, suck out most of the water, put plants, decorations etc in 1 or 2 buckets. remove gravel and place in another bucket. suck out rest of the water, remove bad tank. put new tank in place, and start putting gravel in, then plants/deco etc, etc. down time might be a few hours, wont even lose the beneficial bacteria. get water to temp, add in fish.