Got it running last night- Had to sand the aluminum a little to get the LEDs to slide in to the tube. Set it to 300ma and was reading about 110F on the end of the heatsink this morning, after about 10 hours of running. So a little warm, but not too bad.
I wrapped it with mylar to block the light. Had to steal a space blanking from the camping stuff, couldn't find any other reasonable source. Works well for blocking the light, very little leaks though.
Put in a mostly dead ball of chaeto, will see if can grow at all. I love how I can look down through the tinted top and see what's going on inside.
I'd recommend going with 1/2" fittings for better flow, I'm at about 250ml/min flow rate.
I'm planning on going with mineral oil immersion when it's time to turn up the power. I don't want to fry the LEDs, and I'm thinking it will get too hot if I go up any higher. I have stoppers on order, so I'll just fill the tube with oil and see how it goes. I expect it to transfer heat to the glass tube a lot better, so I should be able to run it at full power if I want to nuke the algae.