Looks nice and clean! The only issue I see is that you will probably need to build a separator to keep the roots from holding that float valve down and causing the buckets to spill over. I built a reef tank from scratch years ago that had a self contained sump in the stand, where I grew chaetomorpha to remove phosphates and nitrates from the water that flowed through the sump, and even with a separator with slots cut into the bottom it would eventually find it's way to that float valve unless I checked on it weekly.