Rex Grigg style Co2 reactor
I used an elbow to get the 90 degree angle rather than getting a 90 degree barb in hopes of helping flow a bit.
Note that mine is 2' long, longer than it otherwise would need to be because I can't run it vertical. I figured the extra length would give the gas more time to dissolve since the reactor sits at a 45 degree angle behind the tank. This is running on the output of my XP3 but may soon get its own dedicated QuietOne 300gph pump.
I went from 4bps with a Rhinox ceramic diffuser to 2.5bps with this setup on my 55g tank (almost killed my fish because I didn't turn the Co2 down when i installed the inline setup). No bubbles coming out of the spray bar, a huge improvement over the snow globe look I had with the Rhinox.
Anyways, cost was $15 and took me 10 minutes to put together, well worth it.