This article will give you insight into some of the popular ways hobbyists are automatically dosing their aquariums and help you on the road to total aquarium automation—freedom from tedious and messy manual dosing or top-off!
http://blog.marinedepot.com/2015/01/dosing-pump-reef-aquarium.html
Be sure to check out the companion post, "How to Set Up a Dosing Pump" once you're done!
http://blog.marinedepot.com/2014/10/dosing-pump-how-to-automate-dosing-reef-tank.html