Guys. I wanna ask you a question about a spray bar for the mist method.
I have a Rio 600 RVT and a spray bar. After 3 days almost all holes in the spray bar are getting plagued up with tiny parts of my plants from the tank.
How are you handling this problem in your tanks? Are you taking it out to clean that thing often or maybe you`re using some kind of the pre-filter on power heads?

When I was doing this I had similar problems, including brown algae growing inside the spraybar. The inside stuff would partially dam the flow and cause the tiny CO2 bubbles to coalesce at that point, ruining the CO2 mist effect. I solved that problem by getting rid of the spraybar. I switched to just sticking the CO2 tube into the inlet grill of my little pump, so the pump rotor would chop up the bubbles into microbubbles. That worked great, but the inlet grill would get stopped up by plant fragments, roots and snails too easily, causing a big drop in CO2.

Now, I have a bigger powerhead, a Maxijet 600, with a sponge filter on the inlet, and the CO2 tube stuck thru the sponge into the sponge support grid. For a couple of weeks now that is working great. I have it mounted upside down in the tank, with the sponge on top, so I can remove and clean the sponge more easily. This is from a suggestion on the Planted Tank Forum.

I use a MaxiJet 750 also and tried it with a spraybar and a venturi-reactor, how do you make the microbubbles reach the whole tank without the spraybar?

I doubt that the microbubbles reach the whole tank, but the CO2 enriched water certainly does. The flow from that powerhead is huge for a 29 gallon tank. It seems, at times, to turn the tank into a whirlpool! Ok, I exaggerate, but there is a lot of flow in that tank, so the bubbles reach everything except the far corners. I have to admit that my DIY genes are now excited again, and I am pondering making a small spraybar to spray the water down the length of the tank at the front, so the water returns along the back, hopefully without quite the whirlpool effect. The much higher flow rate than I previously had, in the same diameter outlet pipe might prevent the algae growth inside it and the coalescing of CO2 bubbles.