The Green Man System Brain Controller Unit, is basically the brains of the whole system. It controls, with exact precision, how and when you feed your plants, which is absolutely critical when producing high-quality specimen crops. It works by pulling through water and nutrients from your reservoir tank and delivering to each individual pot you’ve got connected to the brain whilst keeping your water levels at optimum capacity whether you’re running a combi system or a flood and drain system. You set the feeding schedule using the Grässlin timer mounted onto the electronic control box to tailor the feed to suit the way you grow.