Thanks for the comments. Those bugs have never bothered me, they seem harmless. i can't find any of the fish in there, not sure if theyre hiding or what. The waterfall is just stacks of slate built up like that. Didn't cost me anything as I had pieces to use laying around. I just stacked them up, and used some bricks to support them underneath inside the container. You can't see the bricks unless you really look.
Okay I'm stupid, so.. just a pump going to the top and cascading down via slates? Did you just piecemeal everything together or did you do anything special?