Python's are nice, but they are a waste of water.
For all my tanks I drain water with a PVC U tube with fish guard, and vinyl hose out the door, or in the tub. On the end of the tube I have a garden thread ball valve. I use a drill pump to pull the water out of the tanks, as this is MUCH faster than waiting for gravity. When refilling, for smaller tanks (less than 100 gallons), I hook up the same tube up to the sink faucet, and add dechlor. For larger and taller tanks, I use a trash can full of water, and 5 gallon buckets that get dechlorinated before dumping. I fill the buckets in the tub (tub faucets pump more water than sink faucets) and dump them into the trash can. I have a 1/4 horsepower pump in the trash can which pumps 1050 gph.