I agree with Bill about the pressure issue. those dimensions could potentially make the glass have to be fairly thick driving up the price, course its custom so w/e. But also if you (and I really mean Jack) are planning on making a stand for the tank make sure its built extra strong because the height being so tall means a lot more weight over a smaller surface area so a lot of downward force on your stand. So you will probably not want tile under it as the stand could crack it. maybe? And then the only other potential problem I see with a tank this deep is flow and filtration. On the 6 foot deep tanks that I have cleaned and worked on the problem is getting good flow and even intake along the full length of the tank. It will be more important to make sure you keep the bad stuff suspended so it doesn't settle because that will make cleaning that much more difficult. If you have a standard overflow box this will negate some of these issues. but keeping the flow good without dead spots or areas of super high flow could prove problematic depending on how you go about it.