I am using it to automatically refill my ATO reservoir. I eventually will add door sensors to automatically turn my sump light on whenever I open my stand doors. You can also use it to add manual switches to your tank like light switches and stuff.
Yah theres a fuge. It's a trigger systems Ruby cube 20 so it has a much different layout than a traditional self built sump. The only mechanical filtration I use a skimmer.