I have been brainstorming and researching for the past few months on building a custom aquarium controller using an arduino. I've seen things like the Apex and others but I feel like I can do something better for about a quarter of the price. Right now the design would be to: monitor tank temperature (possibly at multiple locations, perhaps top and bottom) monitor room temperature use the tank temperature to control the heaters and prevent over-heating temperature status lights to visually alert if the temperature is out of the desired range (Blue=cold, green=happy, red=hot) float-switch to notify if water level drops (leak) Under tank water alarm webcam image of the aquarium (from inside the tank) organize all the data into an excel file and automatically email daily updates, track changes automatically send an email alarm if one of the above triggers fires Other features I would like to include but am not sure of the best way to do it is a pH, ammonia, nitrite, and nitrate probes. If used on a planted tank the gH, kH, and dissolved C02 would also be nice to track. Perhaps long-term I can do something similar for a reef tank. Some measurements that may be nice to track over time or features to include on a reef monitor that I could think of would be: Salinity Conductivity Calcium PAR meter (although this may be difficult to hide) Some alert on a protein skimmer? light controls (this wouldn't work with my current systems but if you built them together from the start this would be nice) pump controls I'm curious, what would you like to have automatically tracked in your aquarium? If anybody has any experience with this type of project I would love to discuss it with you.