It either needs treating with a biocide or softwash with a hypo mix but obviously you need to ow what you are doing , pressure washing will only remove the surface spores unless the algae is killed it will return again quite quickly
Could you recommend a brand of biocide please? Thanks
puresealservices.co.uk
Benz is good , and algo clear pro . Probably go with the Benz to be honest , have a look on their web site there is lots of information on there .
When I need to use a biocide I've always used Bio Cleanze because I know I can rely on it. The Benz website now has a UK based site for orders but they only sell it with a minimum of 5litres. You won't need that much and it's not cheap but Rutland Pumps also now sell it by the litre which is probably ideal for you. That can be diluted to make up to 40 litres (this time of year). Personally I use it a bit stronger than that but be aware you may have to wait a while to see the results depending how heavily colonised it is - but it will remove the algae and keep it that way for 12 months+ which is good selling point. Charge appropriately
Thank you will have a gander I have an cline machine with chemical pump in so will have a trial on it.
Bio spray on and leave to work , watch there videos but make sure you are watching the bio video and not the lightning cleanse ones as the process is different
I'm always very wary with render and if I was going to use a brush/broom make sure it's soft bristles anything too stiff could scratch it or leave indents possibly
