This is my second go-around with a reef tank. I took an extended break while working and now that I have retired, I decided to jump back in. The design outlined here has evolved over many years of having aquariums. I tried to come up with a relatively fail-safe system that allowed being away from the tank for vacations and not worry or wonder about the status of the aquarium. With the availability of the controllers/monitors on the market, much of what is described here could be simplified; however, there is a satisfaction of developing and designing from the ground up. Also, I like having multiple controlling subsystems and not a single control point of failure that could affect all the subsystems. I do have a monitoring system that I developed over the years that has served me well. I recently put this design out on github for anyone interested. The link is Aquarium-Monitor. Instead trying to explain my design with pictures of the aquarium, I would like to start with some diagrams that I created that explain the electrical and the fluid systems. I can follow-up with some actual pictures depending on the interest.
