The pond thermometer measures the temperature of the pond water. The temperature determines which food can be fed and/or whether aeration is required.– 5 – 10°C: Feed once a day with special winter food.– 10 – 18°C: Feed daily.– > 18°C: Feed several times a day.– > 20°C: Aerate to prevent oxygen deficiency.– < 6°C: Aerate to prevent freezing.