I didn't vote in the poll since I wasn't sure how to include my "buckets"
I use a 30g Rubbermaid Trash can with an installed PVC drain for removing water from my tanks. It is on a Rubbermaid wheeled dolley making it easy to wheel around between tanks and to the floor drain. It also comes in handy for soaking driftwood
I also use a 40g Rubbermaid trash can on a wheeled dolley for aging tap water or making up replacement water for my tanks.
Oh jeez. I have two ~5 gallon buckets that I use to bring into work and fill with RO water. I add two of them and 1 more of tap water to a ~15gal bucket to get the correct water hardness. I use a ~10gal bucket to drain the tank twice a week, and refill it with the water in the 15 gal. I use the bucket on the stairs behind the tank, syphon it in technique to fill the tank. It can be a little difficult lugging all that water around the house and the car, but it buys me time until I can get an RO system or something better.
I user 4 five gallon buckets to remove the water then I use 3 five gallon gas(water use only, never had gas in them) cans I bought to refill and premix everything in. I am contemplating getting rid of the gas cans though, it's a lot of extra work to fill them and mix everything into them. I think I am going to find an old pond pump and use a 20gallon Sterilite as the refill container.
i have a python but i still use many buckets, i have 2 5's and an extra high 5 gal bucket size(prolly like 7 gallons) but now i have 0 cause i used them all to mortar and grout my new kitchen tile. they are now mortar and grout buckets.
i use a five gallon bucket and one gallon pitcher. i use the pitcher to empty the tank after i've vacced it and then use the bathtub to fill the bucket back up to refill the tank. pain in the butt! sometimes, for my ten, i'll just use the pitcher and the bathroom sink. when i get bigger and better tanks, i'll prolly invest in a python, which is what i used when i worked at petsmart.