I haven't sanded but wonder why you want to.
If its a general clean-up before recoating (with something) I would give it a good scrub with a hard bristle deck scrubbing brush (google will find them) will get the rubbish out.
It all depends on how bad it has become and also what it was last coated with. If an oil finish then a pressure washer should do followed by scrubbing with an oxalic acid deck cleaner to help bring back the wood colour. Sanding should be a last resort if it's really manky. Sanding will also take the coating off the screw heads and will cause rusting later on.
Then there is the New Zealand approach. New Zealand Decking Advert - YouTube
Regards
John