ATO-modification for 2nd fail safe

[nuj244]

Most of the complaints i read from ATO users is the lack of secondary float sensor in case the first float sensor malfunctions/stucks. This is my worry too! What if the sensor of water level stucks? The pump will constantly top up water to the tank until it overflow or the reservoir is run of water which means flooding in the floor. The float sensor for the reservoir (to stop the pump if water at low level) is actually not needed if you have a big reservoir and you know your daily consumption so you can schedule replenishment of transferred water. This is what I did to my set up. I cut the wires of one of the sensor(1) and cut one line of the other sensor(2). I then soldered sensor(1) to sensor(2) so that both sensor are in series. With this arrangement, pump will be activated only if the two sensors are in down positions. This is also useful if you are monitoring two different levels of water like in my case. I have one in the last chanber of my refugium and another one in the first chamber. The one in the first chamber (with floss) is acting as the secondary sensor whch will stop the pump if in case chamber one water flow clogs and water level goes up to a certain level.

The sensor can only be mounted in a certain position if the accompanied holder is used.I just used a magnet cleaner for accurate positioning of the sensor.