Poynters Pool Magic
A single dose, one step-pool, monthly sanitiser that is chlorine-free, matel-free and biguanide-free. It is harmless to humans but is a long term disinfectant, killing bacteria, viruses and algae.
It has no smell and is not affected by sunlight. It lasts up to 3 months with a single dosage and is effective when dosages fall as low as 20% of full strength.