Blue Lagoon Block out blue pond dye 125ml

Reduces algae by reducing light penetration naturally and filtering UV light from the sun, reducing algae growth. Dosage can be increased as required without harming fish but may affect plant growth. Does not contain any methylene blue, fungicide or algaecide. Contains: Polymeric colorant developed in the USA. Add 5ml to 150 litres of water. Always shake well before use.