I had a Reefer 250 installed a week and a half ago and I had a problem with the included float mechanism for the ATO. The water level in the pump section of the sump was too low, the ATO was not replacing the water and the pump was partially exposed, sucking in air and blowing out bubbles. I spoke to Red Sea and they give me detailed instructions on what to do, it is a real royal pain in the butt to take the float apart and raise it.
I also suggested to them that considering the high price of their tanks they should also offer a sensor type ATO setup as an option the same way they sell the Ai Hydra lights in their Deluxe models to replace the basic float that is included in their systems.
Please keep us updated and let us know if you have any more issues or if you decide to replace this ATO setup.