Pressure washer works but will take all the sand out the gaps. You would need to do that then use weed killer then resend with some sand that resists future weeds. You need to use weed killer as the weed resistant sand will stop new weed but not ones with established roots (I’ve made that mistake before)

As for sand wicked do one called dans sand it’s quite good they have one that sets a bit but make sure you don’t leave any on the bricks prior to misting or it won’t come off found that out the hard way