[Rich Wilts]

Darren, Ive got a large marquee to look at to give a price for cleaning the outsides and have had a look through the forum regarding this. There is a historical post you've contributed to where you suggested if it's tree sap and black grime making the marquee dirty instead of green algae then to use Sodium Hypchlorite.

Tell me about this stuff 

Its bleach isnt it? How do you apply it, how dangerous is it, and how effective is it? Fill me in.   

Cheers.

[Matt.]

I been using it today, upto now I only used it on hard floors ( blocks concrete etc ) pressure cleaning, I find that it's best left down for 20-30 mins before cleaning off.

I haven't used it on materials like marquees so be careful, 15% strength

Prob water it down 1/5 to start with and increase as needed, cost wise about £20 for 25 litres

I would be more inclined to try virosol first but if hypo does the job happy days and hypo is cheaper than virosol

[Rich Wilts]

Ive just been to look at the job. I dont think it needs virosol let alone hypo 

Its a large marquee, total roof space 360 metres but they only want one side of the roof cleaned. Its plastic, not fabric and there's very little green on it.

[Matt.]

5L virosol costs about £8, it will help

That pic has been sprayed with virosol, it was an inch thick with heavy moss, literally just wiped off, before I used virosol I had done about 20 of these and they was a nightmare