The Neptune Systems Dissolved Oxygen Module monitors realtime dissolved oxygen in your aquarium water. Of all the organisms in your aquarium, large fish are the most acutely at risk to low O2 levels. In some situations with heavily loaded systems, simply the failing of a skimmer can bring the O2 levels down to dangerous levels and cause a chain-reaction fish die-off . This is where the PM3 Dissolved Oxygen module comes to the rescue.
Should your aquarium O2 start to approach the danger zone, the Apex can alert you immediately by audible alarm as well as send you an email. But, that’s not all. You can have a couple of air pumps with air-stones on the ready in your sump and the Apex will turn them on if the O2 starts dropping too low. While the cost of the PM3 is very reasonable, the down side is that the DO probe itself is relatively expensive. The DO Probe certified and sold by Neptune Systems is a lab grade device and costs about 5x the cost of the PM3 module itself. The good news is that the probe has replaceable membranes so you don’t have to throw it away when it wears out like other probes. Instead, every three months you simply put a new membrane in the probe.
Other features of the PM3 are that the device has 6 digital inputs for float switches, water on floor sensors, pressure sensors, etc. The PM3 is capable of having full datalogging support in Apex Base module.