I was reading a local website today and found someone using sodium metasilicate to clean roofs.
All of the RCIA certified masters including the ARMA and shingle manufacturers do not recommend using this chemical.�
It is too alkaline with a ph of 12.5-13, which is too corrosive and damaging to asphalt shingles.� It will soften and melt the tar/asphalt, decreasing the longevity of the roof.
For those of you using TSP substitute cleaners, check the ingredients to see if sodium metasilicate is in it.� If so, STOP using it!�
It's not as bad as sodium hydroxide (ph 14), but it's still not good.
The best roof chemical concoction using sodium hypochlorite should have a ph of around 11-11.5, using tri-sodium phosphate.� Without TSP, the ph will be lower, and will still work well using isopropol alcohol (Apple Cider).