For larger tanks, hard-plumbing an automatic water change system is the best solution. For smaller tanks, even a Phyton/Water hose might be overkill.
For my 10 gal weekly water changes, while the water drains into a 5 gal bucket, I fill it up manually with tap water using gallon juice bottles. That works fine, and it takes me only 20 min if I don't start doing something else in the middle of it.
To make this a bit more fun, I came up with a slightly improved concept, which involves (besides the 5 gal bucket) a water pump to pump the 5 gal into the tank, and an overflow, made out of two XP3 inlet parts, an acrylic U leftover from bending experiments, and a few pieces of hose to put it all together.
In the cap on the first loop (which sticks into the tank) I added a piece of hose and a check valve for priming ease.
So here is how it works:
1) Put the pump into the bucket filled with fresh water, hang the inflow hose (black) into the tank.
2) Close both caps on top of the plastic pieces. Close the outflow hose with finger, suck on check valve until we have siphon and a mouthful of tank water.
3) Remove finger from outflow hose and cap from second loop. Turn on pump and enjoy your water change.
Now the question becomes what to do about the mixing of new and old water. There are three options that come to mind:
1) Use two buckets... another empty one to catch old water
2) Use one bucket and just keep it running until it is mixed well
3) As pictured, I used an empty trash bag to catch the old water, while the pump moves only the new water into the tank
This can be surely improved... maybe half-hard plumb it to the tank, with a ball valve to shut off the flow securely, and some quick disconnects... maybe an Aqualifter to purge any air in the first loop (instead of tank water tasting)... maybe instead of draining into a bucket, draining into a drain...