Thanks for the reply Tom. I've always used canister filters, so I'm pretty pump illiterate. Could you suggest a pump or two? Looks like I'll have to nix the idea of using a small in tank pump to get to the 400-600 range.
I have a Maxi-Jet 1200, so I tried it. Power head is near the surface and I loop over the tank rim to the Mazzi, then back over the rim to a spray bar for the return. There's little flow, but the mist that comes out of the return is extremely fine - much finer than the results I get with the Kent Marine venturi on my other tanks. The suction on the CO2 line is so great that it collapses the silicon line I was using and I switched to some Tygon tubing I had lying around. It is obvious I'll need to get a stronger pump to get enough flow to get the CO2 level up. I'm wondering if I got the wrong model of Mazzi? This is for a 75g.
Maybe I should cut my losses and get a needle wheel pump like the small Octopus you reference in the needle thread. Might be a lot simpler.
As always, thanks a bundle,