This aquarium is simply a looker. The beautiful white curving lid looks very elegant. You "activate" The various small openings themselves as needed can be very well thought out. Front and rear flap 1 large 2 small. So you can get anywhere on it. The only problem is that my machine can only establish a feeding difficult because the entire cover is curved. But the Eheim machine I've bought holds thanks Velcro fastener. Even the inner filter chamber with the heating element are elegant and sophisticated. By matching cabinet a perfect unit in my office.