Matala UV-C Clarifiers are designed for Koi ponds and water gardens to help suppress blooms of suspended green algae, harmful bacteria, parasites, fungi, protozoan and viruses. Even in a balanced pond ecosystem, sudden blooms of such organisms can occur due to abnormal changes of weather, fish feeding behavior, mineral nutrient levels, etc.
Summer usually means increased pond water loss due to evaporation, which of course leads to topping off our ponds more. You should always add dechlorinator when topping off the water level of a pond. Any amount of chlorine (such as that found in treated water) can be harmful to your fish. Even if it is not enough chlorine to mean immediate death of the fish, this chlorine can still cause harm to proper gill function.