SmartSeal Patio Cleaner Xtreme - 2 x 5L - Powerful Black Spot Remover Patio Cleaner & Rapid Mould Lichen and Algae Remover for Cleaning Stone Paving, Concrete, Sandstone, Porcelain, Slate & Granite

I seldom leave reviews but felt compelled to write this one. I had a new garden path laid three years ago, at some considerable cost. It is a pale Indian sandstone. We started developing immediate black spot problems and three years later, you could not see some of the stones for the black, they were completely covered. Power washing didn't touch it, and the path looked terrible, with a cloudy finish and masses of black spot all over it. This morning I received this product, put the protective gear on, and thought I will spray neat on the really bad bits and then do a 1:1 dilution and do the rest, as I was worried I wouldn't have enough. As I started to spray the neat product, I did about five stones, and then turned back, and good god, genuinely, the black spot had gone, literally gone. I've now done the rest of the path, with a mix of neat and diluted, and it's like new. This is one of the few products I've ever bought which actually does exactly what it says it does. I will be buying more and using it when required if it comes back. If your patio or path has black spot, honestly don't hesitate, this stuff is brilliant. Totally and utterly worth it. Update, bought again this year, due to the mild winter I had really bad black spot again, I power wash first and use this simply for thr black spot. Put it on in a 50/50 dilution, and the black spots just disappeared , bringing it up like new. It’s like a magic eraser. Brilliant product.

Very impressive results and surprised given the disappointing results of other "patio cleaners" that I had tried. This product, although expensive does the job, well recommended.

Great product, does the job, got rid of all the leaf stains from my patio and all the green algae. Just wish it also got rid of rust marks but never mind.

For those looking for decent patio cleaner for black, white and green spots, and black staining, this is the ONE. Having tried all the usual stuff from all the DIY stores etc. this stuff actually works. From what I understand the reason for this is that this stuff is too strong to be sold over the counter and its regulated (at least that was what I was told in a highly regarded 'tool' retailer), hence why you can have it delivered. Only thing I would say, is where appropriate protection, this stuff is serious.

Really pleased with this product. Have used numerous other patio cleaners before and they haven’t really touched it. I dampened the surface as as per instructions. Applied the liquid 50-50 with a sprinkling water can. Because my slabs are bevelled , the dirt sits in between the ridges so I Scrubbed over each slab with a wire brush. ( purchased on Amazon - see review.) as soon as I applied it… I then left it for 1 1/2 - two hours and then rinsed off with a hose pipe with the spray attachment. Unfortunately, I don’t have a before and after But I attended a during and after.. Delighted with the results. The only thing it did not remove , was a few black spots, but I was expecting that. If it helps how much to use - I purchased 4 containers and used one and a half for the area that you see.

The pictures speak for themselves - the horrible grey black streaks in the Indian stone were still there AFTER power-washing. I applied the product almost neat with a spray and it started working immediately. I left it a couple of hours and am thrilled to have the beautiful colours in the paths and patio back again. Regarding the application - easy peasy with a spray, I gave it a light brushing but don’t think that was essential, no ruined clothes and the bleach smell ISN’T that strong. Could probably have diluted it as I didn’t have enough to finish the job but I made the choice to save on effort! I bought direct from Smart Seal and had problems with the delivery. Within three hours of leaving feedback, the seller contacted me, apologised profusely and refunded 30% of the cost - even though there is no delivery charge and I said there was no need. Delighted with the company and the product. It’s up there with the Vileda 1-2 Spray mop which is a life-changer!!

Really good does what it says on the tin or plastic container in this case

Brilliant it got rid of all the black spots and it came up clean well worth the money

Absolutely unbelievable. This works so well and so so quickly. Used on my patio which had lots of black spots and dirt. It came out like new. A little brush after application and it’s brilliant. Very fast delivery working 2 days.