[surrey pressure clean]

hi there iam just asking what chemical to use on one of these new dome shaped conservatory i have been asked to pressure wash one in a school the promblem is it has black water stricks down it. also what price to charge it is in the shape of a rugby ball

[preston powerblast]

Good old TFR (traffic film remover)
But watch you dont pop the seals with the power washer.