Neptune Systems

Lab Grade Conductivity/Salinity Probe

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Start Measuring Salinity in Your Reef

Replace an old probe or add salinity monitoring to your Apex Aquarium Controller. Maintaining consistent salinity in your aquarium is key to the well-being of every organism inside it. Often, we're so busy that we overlook changes in the salinity of our reef aquarium until problems arise. With real-time salinity monitoring, you can be alerted to potential issues and do something about it.


No Salinity Port? No Problem!

If your Apex doesn't have a salinity probe port, you can easily add one with the separately available PM2 Salinity Module. The PM2 Features a salinity probe port, temperature probe port, and an I/O port.


Use the Right Calibration Solution (sold separately)

For Saltwater: 53000 µS Conductivity Solution

For Freshwater: 447 µS Conductivity Solution


What's Included?

1x Neptune Systems Conductivity Probe

More Information
UPC 696859111280
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Product Questions

I just bought the Apex pro A3 and want to add tracking salinity. It has a place to add a salinity probe but do I need to also purchase a module for it or can I just plug the probe into the apex?
Question by: Rebecca Barr on Dec 31, 2022, 10:02 PM
You can simply add this probe directly to your Apex Pro system to track salinity.
Answer by: William Reed (BRS Staff) on Jan 12, 2023, 10:22 AM
Been thinking of my old aquacontroller with apex - has the salinity probe been upgraded recently - seen a lot of negative reviews in the past and hoping it’s fixed
Question by: Rich on Dec 13, 2021, 1:51 PM
Thank you for your question. There haven't been any changes or upgrades to the Neptune Salinity Probe. Most issues users have are due to bubbles or the probe getting dirty that cause inconsistent or incorrect results. I would recommend using the VCA Salinity Probe Stability Kit found here:
I use it at home and it has fixed all the issues I had with the probe.
Answer by: William Glenn (BRS Staff) on Dec 16, 2021, 11:23 AM
Would this prove work with vertex cerebra?
Question by: Shannon Lund on Nov 28, 2016, 3:30 AM
Great question! Unlike pH probes, which use the same BNC connector, some Salinity probes are proprietary to their manufacturer's equipment. For example, the Salinity probe for Neptune Apex will not work with the ReefKeeper and vice versa. :-)
Answer by: Randy on Nov 28, 2016, 7:34 AM
I am thinking of using salinity to regulate my ATO in my new 90 gallon reef I am building with float switch as back up. Do you think this is a valid approach? pros/cons?

Question by: Jon on Aug 6, 2016, 10:49 PM
Hey there, great question. I would not recommend using salinity to be the control of your ATO for a couple of reasons. First, any conductivity probe has a variance of some sort which could be the difference of 1.025SG +/- .002. This could cause misreadings and fluctuations outside of the ranges you desire. Second, conductivity probes need to be calibrated on a regular schedule to ensure accuracy, which means that they fall out of calibration. If you aren't calibrating on a weekly, even daily basis, how can you trust the readings 24/7? Keep it simple in my opinion. Evaporation leaves salt in the tank and takes freshwater out, replace with equal amounts of fresh water and you will be more accurate than any probe could be. ;-)
Answer by: Randy on Aug 9, 2016, 9:44 PM
Can you guys help me please? I'm looking into automating my 75gl reef aquarium. I like the Apex for its wireless/cloud features. Looking to monitor Temp, PH, Alkalinity, and eventually Calcium and Salinity. With all the various modules it can be confusing. Could you all tell me what equipment is needed for the most bank for my buck. Thinking all I need is the Apex Jr. for power supply and can always add on if needed.
Question by: Vincent Maggiore on Jun 26, 2016, 4:28 PM
Great question! Honestly, the most bang-for-your-buck, as far as future upgrades would be the newest Neptune Apex. It offers pH, Temp, Salinity, and ORP monitoring out of the box! :-)
Answer by: Randy on Jun 29, 2016, 6:18 PM
Packing up my apex for a move. How should these probes be stored for long term (about 6 months)?
Question by: David Mastracchio on Mar 20, 2016, 2:04 PM
Great question!
The probes will last around 1.5-2 year maximum and may need to be replaced by the time the tank is being set up, however they can be stored in probe bottles listed below with solution. Feel free to let us know if you have any further questions!
Answer by: Connor on Mar 21, 2016, 6:12 PM
How long is the cord on these? If it's not long enough to reach where I want to put my Apex is there any way to extend the cable?
Question by: Brian on Mar 12, 2016, 9:18 PM
Great question!
These will have a 10.5 foot cable attached. You would need to look into a BNC adapter cable to increase the length. Feel free to let us know if you have any further questions!
Answer by: Connor on Mar 14, 2016, 4:41 PM
Do I need to buy the salinity module in addition to the APEX controller that is $549 in addition to this probe to make all things work best together?
Question by: Alex Chandler on Mar 10, 2016, 2:29 PM
Great question!
You will need the PM2 module in addition to the apex and salinity probe. Feel free to let us know if you have any further questions!
Answer by: Connor on Mar 10, 2016, 4:30 PM
New to the controllers. Wondering if the probe needs to be taken out and cleaned or you just calibrate and put it in your tank and leave it? If it has to be cleaned how often? Thanks
Question by: Corey on Jan 19, 2016, 4:04 PM
Great question.
It is best to clean and re-calibrate the probes. When cleaning the probes should be unplugged and removed and rinsed with water to take any build up off. This can occur once every few months. probes do need to be replaced to accuracy once every 1-2 years. Feel free to let us know if you have any further questions!
Answer by: Connor on Jan 27, 2016, 2:59 PM