Social media should not be used directly to advertise or promote.
Social media like FB is a portal to share things (i.e. photos, ideas, interests). Through the process of sharing you become friends with people.
These friends may share their “like” of you with their FB friends.
If their friends FB you, your page would serve as information for these potential new friends to learn about your wash (perhaps becoming customers).
So, social media can be a market research tool for consumers.
Like a ground up wash, building a community takes time (ramp-up period).
The more people learn about your brand and from others this may open up conversations like on Twitter.
Consequently, I wouldn’t hold much benefit from tweeting about as I would from something like FB.