I have been thinking of switching to bbb for a while, and found the perfect opportunity upon returning to a green hot tub after a week away! Most bleach I have found in UK supermarkets have perfumes amd additives, but Morrisons Own brand bleach has been good in my experience. its £1.29 for 2 litres and states only disinfectant on the ingredients. It added well to my tub and raised the fc level nicely