In reply to GaborS:
> Last week I set up a top rope in the Peaks with no rope protection and the grit stone ruined one of my ropes. yes, at the middle marker! So, I have two 24m dry treated pink ropes if anyone is interested
They'll be really useful for the grit. Just call them left and right, this one, that one... whatever works.
> My question in: is it OK to get a different rope (just one half) and use it with my other (green) half rope, which is in perfect condition? Otherwise I would have to buy a new pair of ropes, but what will I do with that one half rope?
Yes, it's fine. That said, I'd hold off buying one if you climb with others who have their own kit, you possibly don't need it.
jk