Neptune Systems

PM2 Salinity Module

In stock

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Why does BRS recommend this?

Having the ability to monitor the salinity of your reef tank is a very valuable piece of information.  Usually, if something is to go wrong with your tank, you will usually see a change in salinity from temp, to a top off unit being stuck on, if you have a Neptune Apex Controller we highly recommend investing in the PM2 module and salinity probe.


Add the Salinity Module: PM2 to your Apex Neptune System.

  • Real-time monitoring of salinity in reef aquarium
  • Module has extra Temp Probe port
  • I/O Switch Inputs for ATO, feed buttons, leak alarms, etc.
  • Probe Sold Separately.


Features of the Neptune Systems Salinity Expansion Module:

  • Monitor/Control Conductivity/Salinity and temperature
  • 4 Measurement ranges (0-900 uS/cm, 0-9.0 mS/cm, 0-90.0 mS/cm, 0-50 ppt)
  • 6 digital inputs for float switches, water on floor sensors, pressure sensors, etc
  • Full data logging support in Apex Base module
  • Up to 240 AquaBus modules can be added to the Apex system
  • Plug and Play - Automatically recognized when installed into the system
  • 2 AquaBus connectors for flexible expansion via AquaBus
  • Comes with 3′ AquaBus cable
  • Galvanic Isolation for accurate and reliable probe readings
  • Led Status Indicator
  • Upgradeable firmware
  • Compatible with all Apex systems
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Product Questions

i have the apex package that i bought without this module. doesnt the normall apex already measures the salinity. what is the advantage of this probe. does this show specific gravity ?
Question by: michal makarewicz on Nov 23, 2017, 12:57 PM
The Apex Controller System does include a salinity probe, which measures conductivity, and can be directly converted to salinity. It does not show the specific gravity since all the readings will be in a ppt count. This is the same probe that is included with Apex Controllers that come with a salinity probe.
Answer by: Charlie on Nov 24, 2017, 9:35 AM
If I buy this and the salinity probe is that all I need for it to tell me the salinity or do I also have to buy something else for it to work.
Question by: Kevin Haynes on Dec 27, 2016, 9:08 PM
Great question! As long as you have a Neptune Apex, those two items will be all you need! Although, you may want to get a few extra salinity calibration solutions. :-)
Answer by: Randy on Jan 2, 2017, 7:27 AM
What is the warranty on this module?
Question by: Jim on Jan 16, 2016, 7:58 AM
Great question!
The modules for Apex will carry a 1 year warranty. I have included the warranty information on the Neptune site below. Feel free to let us know if you have any further questions!

Answer by: Connor on Jan 26, 2016, 5:20 PM
How does an ATO float switch attach to this module?
I do not see in the photo the inputs to attach the float switches.
I am wanting to use it for both an ATO and salinity monitor.
Question by: Jeff With on Jan 14, 2016, 1:04 PM
Great question,
There is not an option to plug in float switches directly to the PM2. If you are looking for float switches you will need the Apex Breakout Box. The breakout box can plug into the I/O port on the PM2 or the apex main module. Feel free to let us know if you have any further questions!

Answer by: Connor on Jan 14, 2016, 5:06 PM
Hi can i hook up two salinity probes or i have to buy 2 modules?
Question by: Jayson on May 5, 2014, 6:29 AM
Hi Jayson,
If you wanted to monitor two salinity probes you would need a module for each probe (so 2 in this situation).
Answer by: Bulk Reef Supply on May 5, 2014, 6:29 AM
Hi do I need any other probe or equipment to measure the salinity, using that Salinity Module: PM2 - Neptune Systems
Question by: sebastian on Apr 10, 2014, 8:59 AM
Hi Sebastian,
This is the probe module for measuring salinity but make sure to also pick up the actual salinity probe as well!
Answer by: Bulk Reef Supply on Apr 10, 2014, 8:59 AM
Does it come with the slainity probe?
Question by: Jack on Apr 2, 2014, 12:44 PM
Hi Jack,
The salinity probe itself is sold separately.
Answer by: Bulk Reef Supply on Apr 2, 2014, 12:44 PM