[fatman]

It might seem petty for me to bring this up so late, but you did not say what size RO holding container you are using that you intend to use to directly feed your ATO system. With a large RO holding tank there is a possibility of a large amount of water getting pumped into your tank if a control misfunctions and allows the ATO pump to run continous. Well that depends also on the pumping rate of your tank also. I use a small container as an ATO and feed it from a Kalkwasser holding tank. It ffeds water to the ATOby gravity and is hooked up to a float shutoff, not a switch. I mut open a valve once a day to fill the ATO container. That way if the ATO pump runs continously the ATO container water only can feed the tank. Pumping just a few extra a few gallons in to the tank will likely not kill all your inhabitants, but pumping some large contaimners contents like 30 gallons into a tank would likely be much more devastating.
Wow, 225 pounds of live rock. That is like $1500 to $2000 retail or more in Alaska. Up here I would split that between four different 120 gallon tanks. But that is because I pay more for shipping up here than it cost for the rock down here. Lots and lots of Rock! That is great!