Our large U-shaped drive is of tarmac with edging blocks. Both sides are tree lined so every spring we get the early stages of moss forming - basically an unsightly green stain. It's possible but slow to remove most of it with a patio cleaning brush on a jet washer. If I were to use the power jet attachment with the rotating nozzle it would be much faster but I'm sure it would damage the tarmac- you can actually strip paint with it!. Is there a solution I can apply that will effectively kill it or make it easier to jet off without harming the tarmac? I understand Jeyes fluid would probably cause surface damage.