Patio problem

[rickshaw]

I have a patio of rustic style paving flags at the rear of my bungalow that although looks fine in the summer months, goes green with algae over the winter due to lack of sun and wet conditions. I have to pressure wash it off and find that doing this always brings out the sand mixture from the gaps between the flags which then looks terrible.Is there a sand/cement or mortar mixture that can be swept into the gaps easily with a sweeping brush that (1) will stay in place when pressure washed and (2) wont mark the surface of the flags by being applied in this way.

[Bob A Job]

I cant remember the name of it but you can buy a paint on weed/algae killer in B&Q that kills it off and stops it coming back for 6 months. give that a try.

[sylvana]

A patio cleaner called Armilartox will do the job also.

[gazzawazza]

There is a product called Geofix which can be brushed into place and is airdrying. I think it is supposed to set hard but also allow some flexing. http://www.screwfix.com/app/sfd/cat/pro.jsp?id=31817& ;ts=43245#

[rickshaw]

Many thanks all who answered my enquiry, especially gazzawazza who hit the nail on the head by suggesting using Geofix. Have looked at the spec for this product and hopefully this should do the job.