Outer temperature control Touch to adjust the temperature range from 68℉ to 94℉ (20°C-34°C) The heater must be fully submerged underwater, whether horizontally or vertically set up. Do not expose this product to open air otherwise you risk overheating your tank. Error Code and LED Display Blue Light: Temp has reached preset value, now the heater will keep it. Red Light: Heater is now heating. E1: Water shortage or improper installation. E2: The temperature is over 94℉ and the heater will now stop heating. E6: The temperature is over 96℉ and the heater will now stop heating.