Howdy y'all. I just bought this new aquarium that has a weir design I'm unfamiliar with. Usually weirs are sealed to the back of tank, but this one is not and has a glass encasement that houses the overflow and return. My question is, should I seal the weir to back of tank? I'm concerned about build-up in between weir and enasement, but I'm also concerned that if I don't seal it, it will diminish the skimming of weir by allowing water in along edges. Pic included for clarity. Any advice would be greatly appreciated.