Aquariums: 15 years old, thoughts on my tanks?

any advice appreciated 🤍

30 gallon, and 20 long.
30: 4 silvertip tetras, 3 white cloud minnows (im getting more of both, don't worry)
20: 8 black neon tetras
and of course, plentiful snails..

2 tanks running, 4 tanks empty
empty: 10 gallon, 20, 25 octagon and 40 bowfront
the 40 will be an angelfish tank, with various other fish
25 will be a guppy tank, since its mostly vertical..
no idea for the 10 and 20.