I recently switched my CO2 diffusion from a CO2 reactor to running it through a RIO 800 powerhead with venturi attachment. I did this b/c it addressed a couple issues, misting and added flow.
The results with plant growth were tremendous, but I was still battling small cases of BBA and GDA. I figured with regular EI dosing the issue was CO2 so I gradually bumped up the CO2 daily. The algae improved somewhat, but I had my CO2 revved up so fast that it ran out very quickly.
So I did the following.
1. My lighting is a Current Nova Extreme T5 HO 4x55. I had the 4x55 on for 3 hrs and the 2x55 on for 9 for total of 12 hours. I cut it down to 2x55 to 11 hrs. It is raised about 5-6 inches above the tank. Tank is open air.
2. I minimized the surface chop and directed the flow to both sides of the tank with the dual loc line. (Tank is a predrilled reef tank 72g with sump).
3. I halfheartedly covered the sump with black plastic
I succeeded in gassing a couple fish and causing the rest of the inhabitants serious stress once the CO2 tank ran low, likely thanks to the clippard needle valve (plan to replace that). CO2 ran out in 3 weeks. Before tweaking the CO2, I was up to 2 months with a 5lb tank, which I could live with. I also confirmed there were no leaks in the line, I'm also using Tygon from ACE Hardware.
I'm sort of out of ideas at this point, maybe reduce the photoperiod a bit more.