I Ph my starting water down sometimes, Scott even recommends using HERC to drop high Ph starting water, I can see how this would be beneficial due to microbes like a Ph from 6.2-7.2 so droping them into a solution and forcing them into large ph swings can cause death or dormancy. I too used RO just like you are planning and it works great but I have read that fungi don't really grow much in RO water. All the great soil scientist say rain water is the best, or even river water. I'd throw some SEA90 in the RO so your water is not dead and bubble it for an hour or two to get the dissolved oxygen up a bit and then add ingredients.....then sit back and watch the magic happen!! Get your hands dirty or use a sturdy stick about 12 hours into brew and squeeze tea bag, knock it around a little manually....it gets more microbes dislodged and into the solution. Use your nose the entire time, its your best tool to learning what's happening and whether or not the food reserves are getting low.