Cleaning swimming pool crown stones
Super helpful member
Just thought I'd pass this tip on for anyone who has the same problem with the crown stones on the edge of their swimming pool. I bought my house a year ago and the 52 limestone coloured crown stones around the edge of the pool were covered to a greater or lesser extent with black mould spots. I'm not sure if they'd ever been cleaned in 18 years.
After some internet research, I decided to attack the problem with a scrubbing brush using mixture of hot water, washing up liquid and household bleach. Get a bucket, put a good squirt of w/u liquid in the bottom, top with a centimetre of boiling water and about three centimetres of bleach. This mixture is good for two stones at a time. I bought 5 litre bottles of bleach in my local Chinese shop, 2 euros each and 10 litres did the whole lot.
Wear rubber gloves, old clothes and safety glasses, and give each stone a good scrub with the brush. The first few splashes will soak right in, but as you keep scrubbing and adding more, the surface will saturate, and you can leave a layer of the mixture on the surface to slowly evaporate, eating the mould as it dries. You'll see little white dots form over each mould spot as the bleach eats into it. Half an hour later, you should be left with a crown stone in nearly pristine condition.
If anyone decides to try it, let me know how you get on.