wax getting dirty?

I have noticed that the wax on my shortboard gets black and dirty super quick..why?? This is like 3 days of surfing every morning..and i dont even stand on the spots where it is black(except the trac. pad)!
ooooooooooooooohhhhhhh...so dirty..


Also it seems like the wax layer is really thin. Ill be re-waxing it anyways so should i do 1 full pack (2 bars) of basecoat and 1 pack(2 bars) of regular wax? or more?
ooooooooooooooohhhhhhh...so dirty..


Also it seems like the wax layer is really thin. Ill be re-waxing it anyways so should i do 1 full pack (2 bars) of basecoat and 1 pack(2 bars) of regular wax? or more?