Hi Morag. Welcome to justanswer.
Can you please specify which camera are you using?
The process to clean the sand is very tricky and tedious. The cameras pack a LOT of electronics in a very tiny package, and the lens mechanics are buried behind all the said electronics. I would advise you to take it to a repair shop because using a hoover or vacuum cleaner may damage your camera. If you want I can locate nearest repair centers for you.
Reply so that I can serve you better.
Hi, just checking in. How did things turn out?