Tank Depth

Tanks that are shorter in terms of height are more beneficial for a number of reasons! First and foremost, a shallower tank and longer/deeper tank offer the most surface area with which bacteria can grow(ie.deep sand bed where a larger colony of bacteria can grow to handle bio-load). Secondly comes as mentioned above the problem of having to reach your arm down to the bottom of the tank. Deeper tanks(ie.cube tanks) are harder to get at in terms of the depth for cleaning and rearranging. Lastly comes the lighting question. Deep tanks require stronger lighting to reach the bottom of the tank.