Is there a better way of cleaning a patio than just a high pressure jet? Can you get any liquids/powders that help clean it better? They must be out there! Any ideas?
I always use a power wash - saves a lot of effort - apart from power washing you could always try a scrubbing brush and a suitable detergent.
If ti is moss/algae you need rid of a solution of Armillatox available at most garden centres will rid you of it. But is better if you power wash first.
Brick acid is good for cleaning blocks and slabs, etc. You have to be very careful as it is extremely strong, but if you go to your local builders merchants I am sure they will have some and give you the right advice on how to use it.