Thanks BigDave.

FOr 8.25% bleach 121 fl oz jugs, can you tell me how many jugs I should pour each evening?

I am still concerned whether to use the wirebrush or not, they seem very effective, but if it is at the cost of damaging the surface i would be worried. On the other hand, the plastic brush seem not doing the job for me, Ive been using that.

Thanks again!