Nice job it's looking great.
I used this
DIY Theater paint kit it worked great but you have to really, really prep your wall first. I thought I would give it a try before spending big bucks on a screen and I'm still happy with it.
You have to pick the formula based on contrast ratio and how bright the room will be.
With the Panny projector we could watch with all the room lights on no problem but we usually have them dimmed.
We debated curtains for the tank as well but ended up timing sunset to when we usually watch movies. The screen doesn't face directly towards the tank so it's not that bright and there's a moonlight cycle in the tank as well.
The fish are all tucked away in there beds anyway except the puffer and I have never seen him sleeping.
This Telus Optik TV made a huge difference in watching standard def on the projector its much better. But I find after watching HD I don't really look at what's on the other channels after awhile.