Sand doesn't seem to make a difference for the weeds between bricks at my end. I really don't like weedkiller, but it is the only way for me to get rid of it. Having a weed block under the area would have helped, but patio was there before me. Maybe the group in landscaping or patio/deck forums could help.

Our last house had a cobblestone path. Every year I would weed it thoroughly in the spring, and then sprinkle Preen into the crevices. It took care of the problem for most of the summer. Without the Preen, we were weeding constantly!

I have heard that spraying weeds with vinegar will kill the weeds and will not grow back.

patti (who is visiting from the KT...but may become a reg. This is a cool place !!!)

Could you plant some steppables in between the stones?
I had thyme growing between the flagstones at my old house, and the weeds didn't survive...

Here is a link that might be useful: Plants that tolerate foot traffic

A teakettle full of boiling water gets rid of weeds between flagstones pronto.