I use a glass top (I know, but it's personal preference), on my 200 gal Oceanic, so I had to use a little ingenuity, but very easily modified the included mounting of the Tunze 6100's to mount on my overflows. I took the mounting strap/hook of a maxijet and bolted it to the tunze rail with included Tunze plastic bolts. This gave me the low clearance to hang it from the overhead and still install the glass top. I wanted to hang the tunzes at opposite ends of the tank on the overflow surface parallel to the front of the tank, yet face each other. This would require the tunzes to rotate 90 degrees on their adapters. With some creative work with a dremel, I was able to accomplish nearly 90 degrees. So I wound up with secure mounts at opposite ends of the tank hanging off the overflow, with the back of the powerhead butting against the end plates of the aquarium to react the thrust. With the erector set concept of the Tunze mounts, I think that most installation problems could be overcome with some modification,
Mike