Lab Grade Conductivity/Salinity Probe - Neptune Systems

Neptune Systems Lab Grade Conductivity Probe
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  • Neptune Systems Lab Grade Conductivity Probe

Lab Grade Conductivity/Salinity Probe - Neptune Systems

76% Recommend this to a friend (16 of 21)

SKU: 207521
In Stock: 62
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Quick Overview

Salinity / Conductivity Probe – Lab Grade
Start measuring salinity in your tank and get alerts when it is out of range.

  • Replace an old probe

  • Add salinity monitoring to your system via the Salinity Module: PM2


*Calibration solutions sold separately


Full Details


Start measuring salinity in your tank and get alerts when it is out of range.

  • Replace an old probe
  • Add salinity monitoring to your system via the Salinity Module: PM2


*Calibration solutions sold separately

Use 53.0mS calibration fluid for monitoring salinity of saltwater

Use 447mS calibration fluid for monitoring TDS of freshwater


Items 1 to 12 of 21 total

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  • Does not accurately measure salinity in your aquarium By Randall on 8/10/2017

    Even with all the confounding factors that this probe is susceptible to accounted for (bubbles, algae, detritus, electrical noise, etc), don't expect this thing to give you accurate or stable readings. The salinity in a decent size tank owned by anyone with a properly functioning ATO system doesn't change by more than 0.2 ppt from hour to hour, if that. Why then does this unit careen from, for example, 33.7 to 34.9 over the course of a day? Clean it, recalibrate it, reposition it, replace it with a new one, whatever, it'll keep doing this. Obviously the probe isn't measuring salinity. It measures conductivity. So either conductivity does not always equate with salinity (which makes the probe kind of useless for our purpose), the Apex probe design is flawed, or both.
  • Spot on! By FLSharkvictim on 4/1/2017

    When I first installed my PM2 mod with the salinity probe I was getting a reading of 35 to 40 in Fusion and I knew something was not right. So I contacted Neptune and their Superb customer service and they got right back to me about my issue. Anyhow, they told me to go ahead and shake the probes a few times since there could be air bubbles trapped up in the probe. Long story short, ones I gave the probe a little shake a few times, sure enough, the number shot straight up to 55. Word of advice, where ever you install your probes you have to make sure that there are not any air bubbles around them or you're going to be getting a false reading like I was. One of the best pcs for the Apex you can own b/c I don't know about you but I like to know approx where my salinity is at all times. Salinity probe a MUST & the PM2 MOD if you own a Apex..
  • Useless By Jason on 1/14/2017

    Stopped working after about a year or so. Attempted to recal, but it didn't hold for long. Most of the time, shows 0. Not recommeded and I consider it an expensive mistake.
  • Half-ast By Nathan on 12/27/2016

    There are so many issues with the Neptune Apex, this uncalibrated salinity probe is just the tip of the iceberg. Why would you not include calibration solution in the box? It's finicky and you have to babysit the entire system, but what's worse is that we are now in 2017 with only a manual from the outdated 2014 edition. Customer service for anything Neptune sucks.
  • Stopped working....Mistake By Jason on 12/4/2016

    Stopped working after about a year or so. Attempted to recal, but it didn't hold for long. Most of the time, shows 0. Not recommeded and I consider it an expensive mistake.
  • Not Reliable By Milan on 9/25/2016

    In retrospect you really have to think about why you would want to spend over $200 on this after needing to buy the PM2 module, the probe and the calibration solution. The probe failed after 6 months and I am simply not willing to spend so much money on a prob.

    At first it was sort of cool to see micro fluctuations in the salinity between ATO cycles (which are really irrelevant), but after that wore off it became pretty useless. Any notable fluctuations were always caused by the sensitivity of the probe. I was careful not to place it in an area where bubbles could stick to the probe, but I still had to shake it ever so often to get accurate readings. I wanted to use it as a fail safe, as a last resort if my ATO did not work properly. Due to it's unreliability the fail safe actually became the problem and the source of many false alarms. Eventually the probe die and read zero. Complete waste of money IMO. If you are looking for fail safe's, look at adding sanity checks using virtual outlets instead.
  • Good, but stubborn. By Jason on 8/24/2016

    Works great, but can be a little stubborn when first put into water. Pay special attention to instructions and tips on how to remove air bubbles. You need to also have temp probe plugged into PM2 module for increased accuracy.
  • Works well By Button32 on 3/6/2016

    I just like a lot of people had a hard time cal. But did get it done. I think I had a hard time because the solution was cold. After cal. It works great. I used the pinpoint solution after I used the apex solution and it work fine. I have only been using it for a month,but have not had anything to complain about.
  • Solid By Steve on 1/27/2016

    Had to standardize it a couple of times in the cal solution. Then had to tweak my tempt sensor a touch when I moved it over from the base module for temp compensation. Not really a big deal. Readings have been solid and dead on since initial setup. No complaints here.
  • Great By Fishfreak on 2/24/2015

    This is a great add-on for anyone using an apex. I did find out that in order to keep my readings stable is was very necessary to add an addition temp probe to the PM2. At first I was getting crazy numbers and once I added the temp probe it has been spot on ever since.
  • Work great By Chavinpat on 2/13/2015

    Read the instruction and warning carefully. Avoid bubble, avoid others electrical equipment, and more importantly do not knock the probe on any hard surface. It is not hard to calibrate, but be sure to use calibration solution from Apex. I tried other brands, and the reading were off.
  • Fairly stable, but subject to bubble and particle interference By Joe on 1/5/2015

    I've been running the probe for a little more than a month now, and overall it works as you expect. If you place it in an area of the sump or tank that does not have any bubbles, it is fairly stable and accurate. It does bounce around 0.1 ppt, so if the true salinity is 35, you will get values between 35.1 and 34.9, but this is within the spec of the probe.

    I give it only 4 stars because the probe design makes it very susceptible to bubbles or detritus. I use a lot of different conductivity probes for work (i.e. YSI, hydrolab, seabird, etc), but none have this kind of problem. It is a poor design and I don't know why Neptune Systems uses it. You cannot place this probe in an area with bubbles unless you add some kind of protection against them.


Ask a question

Product Questions

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 4:28:00 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 (Admin) on Jun 29, 2016 6:18:00 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 2:04:00 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 (Admin) on Mar 21, 2016 6:12:00 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 4:04:00 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 (Admin) on Jan 27, 2016 2:59:00 PM
Would this prove work with vertex cerebra?
Question by: Shannon Lund on Nov 28, 2016 3:30:00 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 (Admin) on Nov 28, 2016 7:34:00 AM
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 2:29:00 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 (Admin) on Mar 10, 2016 4:30:00 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 9:18:00 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 (Admin) on Mar 14, 2016 4:41:00 PM
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 10:49:00 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 (Admin) on Aug 9, 2016 9:44:00 PM