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Turbidity Sensor Information/Questions

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    • #16627

      Hello EnviroDIY Mayfly community,
      I’ve watched many of the videos that are provided by the Stroud Center. Though some information (which I’m sure will be added in the updated manual) do not necessarily go in-depth about the turbidity sensor (ClariVUE 10) since it is an add-on sensor. So here is some information if you are in need of info on the turbidity sensor:

      – yes, you’ll have to drill a 3rd hole in the pelican box

      More info if needed:

      “Figure 5.2.1 D.  Cable glands (x3).The two large cable glands (1/2” NPT; http://www.mcmaster.com: Item number 69915K53) are for the CTD and OBS-3+ cables. The small cable gland (3/8” NPT; http://www.mcmaster.com: Item number 69915K52) is for solar panel cable. Cable glands allow wires to enter the logger box while at the same time remaining waterproof and submersible. Holes must be drilled and tapped into the Pelican case to accommodate the 3/8” NPT and 1/2” NPT cable glands. The recommended drills for those taps are 37/64” and 23/32″

      Some other remaining questions I have:

      I  noticed that a 4-pin Molex connector is needed for this sensor, which I found on the McMaster website. According to the manual, I did not see the size for this – I may have missed it, as there is quite a bit of information to go through

      The ClariVUE 10 uses C, SDI – 12, or U configured for SDI – 12 for the logging connection, power, ground, and shield.  Do you know what the wire connector size is, as well as the wire configuration for the Molex connector and board connection?


      I had an idea I wanted to run by, would it be okay to add anti-fouling tape to the outside of the sensors (obviously not right on the optical sensor part) to help reduce algal growth etc.? Has anyone done this with their sensors?

      In no way would this prevent regular maintenance but may help deter significant growth on the parts overall. Or would this in some way disrupt the electronics etc.? – Something that others may want to consider when implementing these units.

      Many thanks in advance,

      Emily Mayer

    • #16630
      Shannon Hicks

      There’s a few things in your post to clarify to make sure we’re talking about the same equipment.  The various instructional videos and manuals we’ve released in the past few years cover several different configurations of sensors and cables and equipment.  The majority of the stations we deployed before 2020 had a Meter Group CTD sensor and a Campbell Scientific OBS3+ turbidity sensor on them.  We also used to sell Monitoring Station Kits that contained Pelican 1120 cases that were pre-drilled and tapped for 3 cable glands:  one for solar panel cable, one for CTD sensor, and one for OBS3+ turbidity sensor.  The CTD and old turbidity sensors had cables that required the same diameter cable glands, so we used the 69915K53 size (0.24″-0.47″ cables and 1/2″ NPT threads).

      Campbell Scientific discontinued the OBS3+ turbidity sensor a few years ago and since there was not a ready replacement, we stopped including the cable gland and pre-drilling the holes in the Pelican cases that we sold, since most people were just building CTD-only stations.

      A few months ago, Campbell Scientific released the ClariVUE10 turbidity sensor, and it has a cable with a smaller diameter.  Therefore we recommend using a 69915K54 cable gland (0.2″-0.35″ range, 1/2″ NPT) for the ClariVUE10 turbidity sensor cable.

      The Meter Group Hydros21 sensor can be purchased with either bare wire leads on the end of the cable, or a 3.5mm stereo headphone plug.  We usually tell users to choose the stereo plug because it’s the easiest to use, and we developed a Grove-to-3.5mm-jack adapter board many years ago for connecting the stereo plug to the Grove jack of the EnviroDIY Mayfly.  The ClariVUE turbidity sensor cable has bare wires on the end, there is no connecter on the cable. We developed the multipurpose 6-pin screw terminal board for using bare wire sensors like the ClariVUE with the Mayfly.  You could also use that same screw terminal board for connecting a Hydros21 CTD sensor to the Mayfly if you bought the sensor with bare wires instead of the headphone jack.  It’s worth noting however that we may need to develop a new screw terminal board with some additional circuitry on it to properly communicate with some SDI-12 sensors like the ClariVUE10, so we’re still working on this, which is why we haven’t published official instructions on how to connect a ClariVUE10 to the Mayfly yet.

      The term “Molex connectors” refers to a wide variety of sizes and types of connectors so I’m not sure to which ones you’re referring, but  there aren’t any Molex connectors anywhere on the EnviroDIY Mayfly, and we don’t use them in any of our recommended instructions.  Are you referring to the Grove cables and Grove jacks (the six or seven white, 4-pin polarized sockets on the Mayfly)?  All you should need to connect a ClariVUE10 to the Mayfly is the screw terminal board mentioned above, and a short double-ended Grove cable, like the ones we include in the Starter Kit or the Monitoring Station Kit, or that can be found from various sellers on Amazon.

      Another thing to note, the ClariVUE10 sensors require 9.6v to 18v DC to operate.  The previous EnviroDIY Mayfly boards we sold prior to the fall of 2021 were not capable of powering these sensors.  The Mayfly v1.0 we released in October and the new v1.1 board releasing next week are able to generate a 12v power source capable of powering the sensor, but you have to move the small jumper next to the Grove jack to change the voltage level sent to that jack to match whatever sensor you’re connecting (your options are 3.3v, 5v, and 12v).  So instruction for all these steps are being finalized now, along with writing and testing new code examples for all the major configurations we recommend, which will include the ClariVUE10.

      As for the anti-fouling tape, it’s probably not necessary.  The ClariVUE10 is manufactured with a copper end-plate, so algal growth right around the sensor window should probably be reduced, however the sapphire windows themselves will need to be cleaned regularly, plus we find that the majority of fouling issued to our turbidity sensors is cause by large debris like leaves, sticks, mud, rocks, etc, which is why still suggest frequent service visits to the station, especially for stations that don’t transmit their data to an online portal like Monitor My Watershed.

    • #16636

      Hi Shannon,

      Thank you for the information. I just wanted to clarify something mentioned that may be a roadblock with installing these turbidity sensors. The boards we are using are the Mayfly Data Logger v0.5b (As indicated on the back of the board- pic attached). These will not be able to power the ClariVUE 10, as they only have a maximum voltage output of 5V? Correct?

      Thank you,


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