I use 2 5 gallon buckets to change water in my 125. As I siphon the water out, I'm also vacuming the gravel in my tank. I do 30 gallons each week, and add Amquel and Stress coat to each bucket as I fill it. While I am pouring in one bucket, the other is filling. It takes about 40 miniutes to do the water change. If I am cleaning filters, which I do every other week, it tales about an extra 30 minutes. I have three filters on my big tank, so I do one each week, with one week off each month. Keeps the aquarium clean, and the fish happy.
If I didnt have one, there is no way I could do the WC's on 6 tanks. Itll change your life! (like TIVO) And save your back!