Slap this on your tank. Siphon out where ever you want the water to go, eg, your lawn. Once drained to whatever level you want, take the drain end and attach to the shower 1/2" threaed end, you'll need a 99 cent adapter from a harewhare store, shower thread to Garden hose and then a pvc thread to garden hose.
You can use 1/2, 3.4" 1" garden hose for slow, faster drain and refill, adjust the refill water to the same temp with hand, your hand is good to about +/- 2 F degrees. when you start the refill, add Dechlorinator/Prime etc............turn off once filled.
I change 400 Gallon worth of tanks(4) in about 2-3 hours, but most of the time I'm cleaning the filters, trimming, boxing plants up etc. The hose does all the work really.
Cost: about 5-6$ less the garden hose.
Flexo Gen are excellent and soft kink free hoses for this.
From here, you can hard plumb a drain and hot/cold water system into a sump for the tank if you want semi or a fully automated water changers.
If you have a smaller tank, say 10 gal or less, dipping a bucket in the tank might be easier, faster. Otherwise, use the hose.