Triton suggest a flow rate through the sump of approximately x10 the volume of your display tank. This is pretty simple to work out. If you have a display of say 70 gallons, you should have a return pump turning over 700 GPH. This turnover rate is particularly high.
My aim is not to discredit the above, but in my experience, having a higher turnover rate blocks the filter socks quicker which means changing over more frequently (although it has to be added that the method doesn’t include any form of mechanical filtration other than a skimmer). I think it comes down to the individual – I like a cleaner sump, and by running a system without filter socks I end up with more detritus than I would like settling in the sump.
Another argument on flow rate speeds is that the slower the flow rate the more ‘contact time’ you create as the water passes the skimmer, UV steriliser etc. I suppose the opposite could be said too – the more water that passes through, the more frequently ‘contact time’ is created. It really does come down to the reefer.
If you are following the Triton Method then go with x10 flow rate, if not then hack it. My return flow is approximately x5 and this is simply because it was easier to set up my auto top off at this flow rate.