The C3 and C6p is a housing with the ability for customer to select their application of choice. The C3 can have up to three sensors installed on the instrument. The C6p can have 6 sensors. An example of a setup could be 6 sensors on a C6p all with rhodamine applications for redundancy or a C3 with Rhodamine, Phycocyanin, and Turbidity applications.

The maximum amount of datapoints that can be stored in the C3 is 64,000 data lines.

No there are no memory cards in C3 or C6p.

Data files are downloaded as .csv so they can be opened in Excel or as text files.

The C3 and the C6ps are self-contained units you can leave in the ocean.
Two options for this:

Our C3 shade caps and C-ray Shade cap has vents for water flow. If it faces up with the sun above, it will saturate the photo diode and render it to 0. It needs to face down to properly work. We no longer offer the C-Ray Shade cap for sale.
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For the C3 or C6p shade cap, they can be unscrewed and removed depending on the application that the customer needs. The cap serves to block sunlight from overloading the sensor diode when reading near the surface of the water, especially for applications of towing. If placing the instrument in open ocean water, it is okay to keep the lid off to prevent sediment and any organics from taking residence in the lid.
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Calibration process is listed in our user manuals (998-2300.pdf), but here is a general recap in text to get the general idea. Customer will need to use our C-Soft software, available on our website if you scroll down to download. Here is our help article describing this process: C3 or C6p Troubleshooting and Setup | Turner Designs Help Center
Once everything is booted up, C3 plugged into the computer via data cable 1st, power cable 2nd, you will see a UI with a calibration tab after selecting the Current data. Calibration process will read your blank solution, typically DI water, then it will ask for your liquid standard solution, it will read and finish.
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For our C3 or C6p Fluorometers, they are not factory calibrated. Typically, the customer can calibrate their instruments themselves based on their samples to get a better reading than what we can provide especially with their DI water blanks. Customers can also purchase certain liquid standards from us or an alternative source to do the calibrations themselves. Calibration Solutions for Various Instruments | Turner Designs Help Center
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The C3 operates within a temperature range of 60-105˚F (15-40˚C) without issue. While sensor readings (e.g., oils or chlorophyll) may vary with temperature, the C3 measures temperature independently, and its internal calibration provides a direct output. Temperature does not affect the C3's RFU calculations for hydrocarbons; any variations are for us to interpret. There is no temperature factored into the C3 RFU calculations of hydrocarbon.

Best method for the C3 to read is in situ (water) or via dispersion. Extracted, like with isopropyl, is harder since it is essentially putting a test tube to the C3 and there’s the high chance of degradation to the instrument with the different uses of solvents.
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We have a Battery life calculator for C3 and C6p's: Battery Life Calculator for the C3, C6P, C6 or PhytoFind Submersible Battery (turnerdesigns.com) Useful to see how long your settings will affect battery life. Most will go up to 25 days, on lower settings for wiping revolutions can go three days more.
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Clean sensor head with warm water and soap to remove organics. Use a soft brush sparingly or soft cloth. Use the brillo pad sponge yellow side not the green abrasive side or another soft sponge.
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External third party dataloggers can cause the string of values to come out all jumbled when connected to the C3 or C6p. Adjust the settings for the datalogger to resolve this issue.
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As the gain increases, the sensitivity increases and the concentration range decreases. Our optical specification guide available on our website also lists the limits at which they can read at: linear range of 0-1000 ppb for Rhodamine as an example. Keep in mind that this gain switching does take seconds to readjust. 998-2381_New

To troubleshoot the C3 or C6p after sitting on the shelf for months, simply interface with the software (C-soft) and choose the current data tab which should spark up all the LEDs and start giving you values in the table on that screen.

Then run your hand past each sensor on the C3 or C6p and see if the value pings (increases). That should be good enough for a quick check after a long period of sitting on the shelf.

Up to customer application. If you are using the C3 or C6p while the pump is on, you would need to adjust the read to be 30 second reads or 1 sec since if it is set too high, it will miss the water packets that come through the flow cap.

Here is the C3 data string below. Information comes from S-0172.pdf:

- Note: Fields for channels 1, 2, and 3, depth and temperature are padded with leading spaces in the case that they don’t occupy the entire 9 character field width

C3 and C6p Automatically manages gains based on fluorescence detected.

Gains are not selectable, they are automatically managed in calibration and measurement.

Assume Cyclops-7F datasheet full scale as the same for the C3 and C6p linear full scale.

Yes the C3's RFU full scale is somewhere around there, but that number may not map directly to the full scale on the datasheet.

Unfortunately, with the C3, there is no “disabling” of the autogain feature. We do not have plans in the near future to develop firmware with a fixed gain selection. We do, however, have many options that would work in a similar way to the C3 if you’re looking more in that direction. C-FLUORs with a DataBank datalogger can do this, the Databank has internal datalogging capabilities. C-FLUOR digital can do this with a computer. Additionally, there are other products like the PME logger, Seabird, and some sondes that can do this fixed gain on a cyclops or C-FLUOR.

Information comes from C3 or C6p Troubleshooting and Setup | Turner Designs Help Center
Ensure that the following conditions below are met.

For the C3 or C6p, 2.20 is standard version installed on the instrument. 2.22 is for integrator version.

This firmware is designed for use by customers that are integrating their C3 with an external datalogger, CTD or similar system. The Integrator Firmware is different from the standard C3 firmware and has some features that users need to consider before installing:

If your application requires the 1 second interval sampling and you do not require internal datalogging on the C3, the integrator firmware would be better suited to your needs. However, the standard C3 firmware can be set to greater than 5 seconds.
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Cables that fit C3: MCIL-8-FS_IMPULSE (Micro Circular Rubber Molded Connector). You can find some examples at Fondriest: https://www.fondriest.com/nexsens-mcil-female-cable-assemblies.htm

Unfortunately we don’t have the cables for the C3 or C6p. They can be purchased online from the following site: https://www.fondriest.com/nexsens-mcil-female-cable-assemblies.htm What you’re looking for is a cable that has 8 pins like the MCIL-8-FS-1. Please let us know if you have any questions. Thank you.
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We typically don’t want two dissimilar metals such as the copper tape and the temperature probe touching each other in seawater, it will lead to corrosion on the C3.
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Unfortunately, we don’t sell that copper tape anymore. You can however go to any local hardware store and cut it out to shape.
We offer copper plates which work better for preventing growth and are a perfect fit for the C3. Another option is the copper wiper, which should be enough at surface level depth applications.

The C3 wiper brush has stiff bristles which can catch on the sides when wiping causing it to reverse. If the bristle points face into the turn direction, the wiper may stop or reverse. To prevent this, remove the wiper, home it using the test wiper button in C-Soft, then reinstall the brush with the bristle points facing away from the turn. This ensures the bristles won’t catch on the sensor/end cap or copper plate.

C3 Battery bracket certainly will help with stability especially if the cable connection comes loose causing pins to lose connection. The unit will start logging 1.5 minutes after power is supplied, assuming it isn’t intermittent power. The one thing I would absolutely make sure of is that the clock is set properly. Setting time to your local time is critical to the unit starting on time.

Sometimes after committing new firmware to memory on the C3, the serial number gets corrupted. It can get fixed if you upload the old firmware and see the serial number return. Though the serial number is not part of the functionality of the instrument and will not affect readings.

On very rare occasions a bug will form in the software when a calibration is written over an existing calibration. This will cause the live data readings to appear like it is 4 seconds off. The best way to get this fixed is to select clear calibrations in the C-SOFT tab for settings.
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Regarding useful life, we have no results that show failure of the C3 or C6p motor after a number of wipes. We’ve had these same units in the field for longer than 5 years without issue. I can’t assume they’ve been wiping continuously for 5 years so I have no data on continuous use, however, that’s a good indication that the wipers last a long time.

Though there is some minor oxidation on the copper elements, they are still fine to use. Only with a complete degradation would it be time to replace the wiper and plate.

We recommend use of the C3/C6p shade cap as it provides a fixed distance for sample measurement and minimizes affects from ambient light. The Shade Cap also offers protection for the optics and prevents damage from deploying, recovering, or transporting the instrument, in fast-flowing environments, and/or from bottoming out in shallow environments.

We have a few recommendations for C3 or C6p maintenance before deployment. To protect your bulkhead connector from damage, a light coat of Silicone spray should be used on the rubber of the male pins of the bulkhead to aid in sealing.

The manufacturer recommends 3M™ Silicone Lubricant Spray or Loctite 8021 spray.

Note: You should avoid using silicone grease. DO NOT USE WD-40 - it will destroy the connectors.

Here are some common reasons why ASCII data output will not enable on the C3 or C6p:

There is a specific series of steps that needs to be followed in order to enable ASCII data output from a C3 or C6P instrument:

First make sure that your firmware and C-Soft software are updated. The most current versions of the software and firmware are available from the Turner Designs website. Once you have confirmed and/or installed the most current version, disconnect all connections made thus far, close the C-Soft program if it is open and follow the procedure article on how to troubleshoot. Here is a quick recap:
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Use our Battery Life Calculator to estimate the submersible battery life based on the sample interval of the C3 or C6p.

C3 or C6p Wiring diagrams for the pigtail cables are available in the Cable Guide.

Instructions on how to use the Solid Secondary Standard are available at http://docs.turnerdesigns.com/t2/doc/instructions/998-2311.pdf and on our online article.

The bulkhead connectors for the C3 require maintenance and lubrication to ensure that they don’t degrade and cause the unit to take on water (leak). Mating surfaces of the connectors need to be lubricated on a regular basis with 3M™ Silicone Lubricant Spray, Loctite 8021 spray or equivalent.

You should avoid using silicone grease.

DO NOT USE WD-40 - it will destroy the connectors.

Other things to remember:

Unfortunately, the software that Campbell Scientific creates would not be compatible with their different versions. Our recommendation is to reach out to the Campbell Scientific Datalogger Support team and get instructions on how to setup up analog and ASCII data strings on their newer devices.