Is it okay to wash away the sand between cobblestones generally? They are not the traditional 'roundy' ones but square ones that interlock/rest nicely to each other.
Well I just power washed mine, and bought some sand to replace what I washed away. If you fill up the gaps with sand, it reduces weed growth. I think, actually after all the trouble I've been to, it had better.
The experts recommend keeping power washing to a minimum, Unless you're careful and keep the jet at a shallow angle, you will disturb the bedding layer, and no amount of replacing jointing sand will fix that.