BAC 50 5L - Benzalkonium Chloride Concentrated 5L, For Roof Cleaning, Soft Washing, Decking and Outdoor Cleaning

I have used it once and will look forward to the results, very easy to use, as long as you follow the instructions.

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I read mixed reviews about this product but as I didn't want to waste water cleaning the decking and paving stones, I was willing to give it a go. So glad I did. As long as you follow the mix ratio and apply when it's dry it works as the company claims. My decking came up like new and the lovely rose tint in my paving could be seen again with very little effort. Someone did mention about it not killing thick moss. It does but if it's too thick/dense it just needs a scrub to remove the brown dead residue. Would recommend.

This is the active ingredient in Patio Magic, which costs almost the same per 5L despite only containing ~7.5% benzalkonium chloride. Buying this concentrate is, therefore, significantly better value while enabling the user to mix a strength appropriate to their own needs.Just like Patio Magic, this stuff took the winter growth of green algae off my patio, fences and walls within a couple of days of application. This isn't the right stuff to kill moss, and it will struggle with algae on rougher and more porous surfaces.

This is a concentrated form of patio magic so dilute at least 10:1. If applied to clean fully dry sandstone and dry for three days after the protective effect lasts very long term. Doesn’t seem to be anywhere near as effective on normal pavers.

I have only used this once, diluted at 10:1, that's 500ml Bac50 per 5 litres of water in a pressure sprayer. Slightly more diluted than suggested on the container. Weeds and moss and algae died within the week on my block paving. It also killed the algae on my roofing felt. The liquid is viscous but mixes easily with water. I would advise wearing a mask when applying with a pressure sprayer as the spray could drift, and also non onto target areas like flower beds. Bac 50 seems to be more affective than other more expensive paving products. I would highly recommend.

It's as thick as wallpaper paste, and needs to be stirred well to mix it properly. Used at 1:8 dilution, it worked very quickly and efficiently to kill the moss on an asphalt drive. Next time I will try it at perhaps 1:20. Note that the moss turned a light brown colour when it died, but still remained embedded in the asphalt. If it's still there in spring, I will try a power washer to see if that loosens it.

Worked an absolute treat at killing all my moss and weeds