Yes it is arduino based but i am converting it to something more basic as the trend of using arduinos to do simple things makes me go crazy. Even though it is excellent for quickly prototyping circuits. No offense to arduino users. I am using solenoids, water pumps and float sensors. My aquarium needs a lot of water changes as I have a discus fish aquarium. When i switch on the water changer fresh water starts to flow in and when the water reaches a certain limit a pump is kicked it. This pump stays active for a certain period after which it stops. This cycle repeats. There are safety measures for overflow and excess water pumped out as well.