No idea, just daw them after jet washing the driveAre the spots organic? If so then try a limited application of bleach.
Any from.amazon or similar?Brick acid. Apply by brush. Leave for 10 min, rinse and repeat if necessary.
No idea, just daw them after jet washing the drive
Any from.amazon or similar?
You can usually only get it from a local building store, becuase these days it's outlawed for the general public. It's basically concentrated sulphuric acid.
They use it to make the pressure washing more effective.
They use it for quick effect despite poor longevity and ignoring damage to surfaces. I started down this road many years ago with companies that would only use ‘hypo’ and realised the compromise so now use a couple of biocides for best results, no damage and best longevity.
My roof, patio, block paving and even fence panels show the benefit of a targeted treatment so I will stick with that.
Could you send me a link to the products you use for this please?
Just google BAC50, its available from chemical suppliers on Amazon, eBay or direct from the same suppliers. Where is best depends on delivery for the quantity you want.
DDAC is also an option but BAC is more commonly available.
Edit: For general use BAC at 2% is a good mix to dilute to for use. For ref: Patio Magic at 1:4 to water is 1.8%, Wet and Forget diluted is about 1.7% BAC
Cheers. I've been using some sodium hypochlorite and it does a decent enough job but I don't want to damage the patio and it's not a really long term solution. I'll give the BAC a try.