Importance of Rockwool ph

My package of rockwool knock-off cubes say that they need to be soaked in water with a ph level of 5.5 or so. I don't have a ph meter available at the moment. How important is the ph factor in order for my beans to sprout?

You will be ok with just tap water. You have to get one once they get kicking.

thanks for the quick reply
I made a simple humidity chamber with a clear lettuce refrigeration box that i found. Will this support adequate humidity till they sprout?

That will work fine. ya may have to poke some holes in it so wont get too hot. I dnt use one my self.