It really depends what type of filter you wish to use.
If you want to use a live rock type filtration then try to aim for 1kg of liverock per 2 gallon (uk) of volume. this is the minimum really and i would aim for as much as 1kg per 1 gallon over a period of time.
It doesnt really work in the same principle as far as turnover per hour when it comes to filtration. Basically you want as much turnover per hour in a reef tank anyway of corals become stressed. A minimum of 10x the ltrs of tank is a good starter (450 ltr tank will need 4500 ltr per hour turnover at minimum).
A reef has HUGE surges which is probably one of the few things we simply cannot match in a hime aquarium, fish and inverts are ideally made for coping in this environment and some depend upon it. Hard corals (sps) create a mucus on their skin that needs to be washed away constantly or they end up suffocating themselves and burning themselves. A low turnover rate will not move this mucus away fast enough, however, if a powerhead is pointed directly at a coral then it becomes fatigued also, this is partly due to the fact that the mucus is stripped too fast and this leaves the corals tissue exposed to the sun thus leaving it vulnerable to UV. High turnover rate is important but try not to direct the powerheads directly at a coral.
So basically in refernance to turnover per hour for filtration is a bit of a mute point as by following these guideline then you will have enough turnover for just about any type of filtration.
Hope this helps.
