I use a system that was custom designed by three grad students at the university here in Faibanks, but they are not diificult according to them. They started out with premade systems and added to them. I receive pH, temperature, salinity, low water level alert, power on/off signals (continuity) for 8 circuits. They are hooked up to cheap lap tops with cable connections through the web to my home computer. I place these on all contracted maintenance tanks. I do not use one on my own apartment tanks. There are for monitoring only, no controls are run through them. They are set up however to run x-10 controls, however I do not use thse do to independability issues. That and I get paid for responses, as do my employees. My units with modifications were around $380 each. You can scab togeter cheaper systems but they are more cumbersome and require several inclosures instead of one. Any electronics person could make the additions for you once yopu bought a commercially available unit. My units were designed and are sold by a collefe professor in the lower 48 states. They are available on line. I willl look up the url.