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Discussion Starter · #1 ·
Any recommendations on a good PAR meter that can be used in a tank?
I need to purchase a PAR meter for some research and I'd also like to use it for my tanks at home.
 

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Discussion Starter · #4 ·
Thanks, In my case, durability and functionality absolutely trump precision if the accuracy is only "good". My students will be using the meter regularly in the field and I don't want to overspend for just a very small increase in accuracy
 

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When our aquatic plant group bought one of the Apogee meters Tom Barr calibrated it against a LiCor meter, which is one of the best ones, and they gave about the same readings. So, it is pretty well the standard meter now for aquarium light measurements. Just making tiny mistakes in how you use the meter will contribute more inaccuracy than the inherent inaccuracy of the meter.
 

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Discussion Starter · #6 ·
Thanks Hoppy and Optix. I'll go with Apogee. I did look at the LiCor, but didn't find any particular advantage to the LiCor, that was worth the cost differential, for my applications.
 

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For a grand total of $30 you can build

Arduino and the Taos TSL230R Light Sensor: Getting Started

although the second part of the article isn't really necessary, as we don't usually convert from energy to illuminance

Arduino and the TSL230R: Photographic Conversions

Follow the in-article link to the chip's source for more good stuff on its construction. And I usually get my Arduino boards from Advanced Micro Circuits.

The open source libraries for Arduino cover a lot of ground - pH monitors, light sensors, etc, all with in-built logging capabilities through USB connections. I intend to "map out" the light profile of an 80-gallon's landscaping across time with a few of these, among other sensors and controllers (CO2/pH, dosing, etc.), using an Arduino-specific control network...
 

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Discussion Starter · #10 ·
How would you calibrate a DIY PAR meter? Calibration is by far the hardest part.
For laboratory exercises with my ecology students and some research applications, I need a meter that 1) can be "factory-certified" and recalibrated periodically, 2) durable for outside the lab [field] use, 3) easily portable, and 4) has a track record of use. A custom job would not work and I need the instrument sooner rather than later.

I do appreciate all the suggestions.
 

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How would you calibrate a DIY PAR meter? Calibration is by far the hardest part.
Same way you would calibrate any other instrument - against a known standard.

The advantage of the Arduino/Sensor combo is that you're counting frequencies with which you're doing math. The math can be factored as necessary. You have control of the software that does the calculations.

And your probe consists of a clear plastic encased IC with attached leads built however you choose to consider durability. The IC is definitely not the standard three-lead part that most attach to their voltmeters and try to whiz by on.

Custom work is often within the realm of research, is it not? The idea is to get what you need to perform the task at hand, and to do so with verifiable, repeatable results. If you need multiple copies for all involved, you can purchase your "factory certified" model as the standard against which all of the custom builds are calibrated, leaving you with but the main, purchased meter to be sent elsewhere to be certified by a party outside your research group.

Of course, not all research is tightly budgeted. If your own budget allows for the expediture of $200+ a pop for each student, then by all means let loose with the money. But then you also lose the ability to teach adaptation in achieving the main goal as well as first-hand knowledge in the construction of your equipment and its limits and configurability.

But do not make the mistake of dumping something simply due to its "DIY" label without actually considering what it is or how it operates. Research history is as full of examples of amateurs and their projects making firm discoveries as it is with government-funded projects, if not more so...
 
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