LLW UV Pond Clarifier This Smartline pond clarifier is designed to kill harmful bacteria and clump and kill algae. This clarifier should only be used from May to September for a limited number of hours. From October to April, UV clarification is not usually necessary. During the first week of use, the clarifier should only be run for four hours a day to prevent sudden oxygen depletion caused by removing algae too quickly. How long should the clarifier be run for? Very murky pond water: 12hrs Murky pond water (can see down a few cms): 8 hrs Slightly murky pond water (can see down 50cms): 4 hrs Features Can be used on ponds up to 12000l Length: 32cm (12½in) x 8cm (3 1?6in) x 8cm (3 1?6in)