Well, time for a fun new project. I am tired of lugging buckets for salt water changes on my 240G. Sure .... I could just add a pump and some extra hoses ... but what is the fun in that. SO : Time to make a fully automated salt water exchange system. (Not a simple auto top off. This will truly drain and refill salt water automatically) Salt Water storage: A 100G tank is already on order. I still plan to mix the salt myself. Maybe someday that can be automated? Exchange plan: The idea is to automatically change about 15% per month. To do that, I will probably have it run Monday and Thursday night, at 7.5 gallons/cycle. Controller: Sure, I could use my current Arduino system ... but this is 2014!!!! Those things are antiques. And besides, the plan is to be OVER designed. So: The plan is to use a Raspberry Pi. Linux based system. Stay tuned for more details on pumps, sensors, and progress. I expect this project to take quite a while, like all my projects do. But I already started receiving some of the parts.