when I first started with fish, I used to use buckets, then when the tanks started getting bigger, I began getting wetter...and the carpets! by the time I got to my 1000ltr tank, I came up with a much better solution. I have two 300w heaters and basically get the hose from outside, stick it in the tank, go outside and turn the tap on, this preps the hose with water, after 10secs, I undo the the hose from the tap and the water backflows out down the drain. I then give it 15 mins thereof and then reconnect the hose to the tap and turn it on. yes the water is cold, but the two 300w heaters kick in and it will still drop temp wise but I have never lost a fish doing it this way. however I do not spill a drop of water this way.