would the ball valve thing be a check valve? Also, you should take some before and after pictures 
I have a power head with a venturi port is that what you mean? Wouldn't that just cause all the co2 to gas out? If you have instructions for a DIY difusser that would be cool. thanks.
There are more if you don't like any of these. But in-line / counter-low is the absolute best route for diffusion efficiency! not JMO but fact![]()