The Brew Cabin

Hi, this is an absolute numpty question.
I've just bought a house with block paving in place its started to go green and slippy and I would like to know the best way to clean it.
Ive tried power wash but yes i have driven the sand out in some areas so I need to know the best way to maintain it as well and with what type of sand.
Any help would be appreciated.

You need to replace the jointing sand as soon as possible, as it's an absolutely integral part of the cosntruction, not merely a way of filling the gaps. You can buy dried jointing sand in 40Kg bags from most Builders Merchants, and then it's just a matter of sweeping it into the open joints, letting it settle for a week or so, and then topping up.

Longer term, you might want to consider applying a sealant. This will prevent the mosses and algae establishing themselves quite so freely, and will keep the jointing sand in place when you do decide to give the paving a power wash. If a sealant isn't to your taste, and not everyone does appreciate the gloss or semi-gloss finish, then keep the power wash lance to a shallow angle when washing down and never aim directly at the joints. There are joint stabilising fluids that are considered in the Jointing and Pointing pages, and these will help keep the sand in place if you decide against using a sealant.