Conservatory

[DaveST]

I have a five year old conservatory that has plastic (uPVC) roof panels. They are now severely discoloured with a green algae. I've tried a pressure jet washer but access is difficult. Any suggestions for something that I can spray onto the roof to rid or control the algae? I also have a number of what I can only describe as flat looking barnacles. Again, they come off with a pressure washer jet aimed at them but it's getting at them.

Dave

[Newt]

Hi Dave,

The green you are seeing is probably moss or algae or both. Here's a couple of helpful sites.
http://bryophytes.science.oregonstate.edu/page24.htm
http://bryophytes.science.oregonstate.edu/page18.htm

The flat barnacle looking things are lichens. They are harmless to your roof and don't do any damage. They may just look unsightly. They are actually beneficial to wildlife.
http://www.lichen.com/animals.html

Newt