I just hooked up my Ista Max Mix Co2 Reactor (Medium) to my Eheim 2213 canister yesterday. Everything seems to be working well. The noise level is low, and the co2 seems to be dissolving 100% (for the most part).
I've looked up videos on youtube regarding the Ista Max Mix Co2 Reactor and it the videos show the top 2 propellers moving very fast. Mine are not; in fact, the top one doesn't move at all and the 2nd one from the top moves very slowly.
After a quick search here on the forums, I found the answer to my problem.
"Once I fired up the system, driven by an XP1, I found out that the top impeller would not spin correctly. I could have let it be, I believe the CO2 still would have been integrated into the system (physics are physics), but I tore it down and started the tinkering. Inside the body there was a small molding sprue issue that left a bump on the top of the unit which was hanging up the impeller. The other units also have molding marks, which will require some cleaning up to function smoothly in my opinion. I took a wooden dowel and taped some 150 grit sand paper on to the end and sanded it down. I cleared the obstruction with sanding and reassembled. The top impeller then spun smoothly."