Hi...I disagree with the you need two people thing. I have had my python for 5 months and it is a breeze to handle once you get the knack. As already posted, it functions almost like an airfoil. Running water past the attachment causes a negative vacuum that sucks the water out of the tank. After you stop your vacuuming, you stop the water, add conditioner, do whatever tank work/cleaning you need to do. Then, run the water 'till it gets to the temp you want. This is where it takes a little practice but NOT A WHOLE LOT. Test your aquarium water with your finger, then adjust your tap to the same sensation. You then place your hose valve on CLOSED, push up the sink 'switch' attached to the sink, walk over to the tank and then open the valve. While you are running the water, test aquarium temp and the python temp. If they are close, don't worry, fish are durable and will tolerate a 1 or 2 degree temp change. If not close, close the valve and walk back to the sink, adjust, and repeat. I will admit tho', that the sink pressure can build up quickly when valves are closed so you must adjust quickly. With this method, my thermometer never varied more than 1/2 to 1 degree. With a 46 gallon tank, and a 25% water change, you really have to be off a LOT to made a temp change that would threaten your fish. Hope this helps. SH