I'm still doing the bucket method, but with two 20s and a 6.6g, it's not really a lot of water. I use a 5 gallon bucket.
As for pouring water back in, I use an air pump shelf. It's a throwback from my fish keeping days in the 70s/80s. It's basically a 5"x6" plastic shelf with two plastic hooks for hanging onto the rim of the tank. I hang the shelf on the inside of the tank, pour water, and it spreads it out sideways.
If I did not have the air pump shelf, I would take one of those hang on specimen thingys (what they use in the LFS
to hold fish before bagging them). I'd drill a bunch of holes in it so it showers the tank with water.
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