I have a 10 gallon species tank for WCMM
a 10 gallon divided with Ted and Regulus (Reg flares at Ted, Ted could care less)
Ted used to be in the 2.5 gallon, but now he's in the 10 so my pretty pink/blue girly is in the new 5.5 where Ted's 2.5 used to be in the kitchen and the 2.5 is empty on the shelf with me having the want to get yet another, but probably going to use it for a hospital tank.
for water changes, mine used to be EASY at my old house, .. gravel vac right out the window onto the side garden! I'd just fill up a 5 gallon bucket, dose with the regular stuff and dump back in, replace fish. Now I have 0 windows in my dining room where most of my tanks are :( .. into the bucket I guess!
I'd love to have one of those siphons that hook up to my faucet .. *dreams*