It [the website] talks about the diffuser made with a powerhead and a siphon.. how would you compare it to the other diffusers mentioned?
namely, the hagen ladder, nano diffuser, the spiral one in the video, and the Spio VIII Co2 diffuser (which looks like a combination of the spiral one and a nano diffuser).
The Hagen ladder works very well, but is large and unsightly at times. Works best in 20 gallons or less.
The Nano glass diffusers and the other types of glass diffusers work well when placed under a flow, powerhead, or filter intake. This maximizes the dissolution of C02 while spreading the CO2 bubbles throughout the tank. Works best in 20-30 gallons or less (with DIY CO2).
The powerhead/siphon tube combo is another good one, which I've been prefering over the others. Dissolves CO2 well, and doesn't require much cleaning like the other two. I would purchase the
Red Sea Reactor 500, since it's small. Works best in 20-25 gallons or less.
Same dissolving principle of the Reactor 500, and powerhead/siphon combos. Power Vortex Reactor at work.
Ultimately, since they all work pretty well, it's based on your preference of look and style.
-John N.