Custom Chemical SuppliesSodium Hypochlorite 14-15% 4x5L, Patio Cleaner | High Strength, Swimming Pool Chlorine, Pale yellow (SH1415-20)

Here's what worked for me. I removed the mud from my blick driveway pointing, then used a jet washer to blast the bricks clean. The black spots refused to budge.Much to my surprise - you have to be sceptical right - this cleaner worked like a dream! I simply used a watering can & a 50 / 50 water mix, and sprayed away!The black spots either disappeared or evolved into grey marks, which another jet wash removed easily.Highly recommended, both for its effectiveness and for ease of applying.

I liked it as worked as advertised And killed the weeds. No jet washing from now on.

I have used this a few times with a powerful petrol pressure washer, it works as well as anything else I have tried. It is always difficult to shift black mould spots with any cleaning fluid. PPE is essential when using this as it is a strong chemical.

Great product for cleaning algae, killing moss and paving slabs. No longer need a pressure washer after using this product. Excellent and will keep buying.

Diluted 4l product to 1l water because we had so much black spot. The black spot had never been treated and was getting progressively worse. The patio is jet washed every 2/3 years but that always left the black spot. I used a small hand held sprayer to apply the product, to avoid plants and the lawn and then left it. This product works with no effort at all! No brushing or rinsing, in fairness I knew it was going to rain later. My slabs are Indian sandstone, they’re porous and absorbed the product.I’m utterly amazed and won’t be jet washing or buying anything other than this again.

Very good product!

Patio looks nice and clean with no effort

This was my first time using hypo. I went with a 5:1 ratio on a sandstone patio. It was a warm day so I couldn’t let it dwell as long as I would on an overcast day.The result is very good, most of the grime and black spots have gone after just one application.Splashes will ruin your clothes, as others have written, use PPE and wellies.