Heres my true companion with regards to waterchanges. Because its so small amounts I change it is enough for me to use this elephant which normally is used to water flowerpots with.
I then pour with one hand and hold the other in the surface of the water in the tank with an open palm (= picnic plate) and pour water from the elephant into my open palm. This way there is only limited stirring up of things in the tank.
One thing I was thinking about with your tanks, Jennifer, are the Java ferns, – these do not like to have their roots in the gravel – they are plants that grow attached to something else like a piece of wood or stone or even free floating.
In some of my tanks which I actually often rearrange I admit I have chunks of javafern that I do not fasten to anything, they just float. The roots then provide shelter for small fry 🙂