“Well designed and reliable auto top off with light sensor. Cleverly uses this single sensor to top off the water, but also knows that if it's taking a lot longer than normal to fill up to stop and set the alarm off (because the pump is probably out of fresh water).
This is our second for a different tank as they are so reliable, also very compact, can use on large tanks down to small nano tanks. Powerful little pump with good head height. The sensor will need a light brush with your finger to remove algae every few months to ensure it continues to work as expect.”
