Thank you for your feedback. The most effective way of making sure you don't get green water is with a UV. The treatments will kill any algae off that is already in the pond, but it won't stop it from growing again. In warmer weather, an algae bloom is more likely and that's what gives the appearance of green water. Treating the pond regularly will help, or you could try shading the pond if possible, or planting lots of plants in there to feed off any algae that grows. If you would like any further advice please get in touch. Thank you.