Light diminishes in an inverse square - ie. with each additional foot, you've got exponentially less light than you did initially (ie. at 3', you've got roughly 1/9th as much light as you do at 1' whereas at 2' you've got 1/4th, and so to provide adequately for bottom corals in a 3' tall water column you need >2x more initial light). To sufficiently light that, you're going to face a lot of issues. All of which besides, anything over about 700mm tall is a pain in the *** to clean - as has been mentioned. In having said that, for a minimalist FOWLR or softy reef it could be quite an interesting base.