PAR meter vs PAR sensor from Apogee

[timmo11]

Hi

Been looking at the posts where people have bought a PAR meter, seems like a great idea to me. I have never come across so much male cow manure as that which is claimed for expensive aquarium lighting.

Now that the group buy is over, it seems to me that if you have an electronic multimeter handy and know how to multiply by 5 in your head, then just buying their SQ-120 sensor is a much better deal at US$139 than buying the whole meter for $250. In fact you could easy buy a multimeter for US$110 and have a lot of change left over.

Any counter arguments to that?

Tim

 

[shoggoth43]

Tim,

Any luck on this? Which did you go with? I think I found the basic meter online for 200$ but saving some green is always good.

-
S

 

[timmo11]

Tim,

Any luck on this? Which did you go with? I think I found the basic meter online for 200$ but saving some green is always good.

-
S

Hi Shoggoth

Yes I went for the sensor. I spoke to a very helpful woman from Apogee who told me that the sensor was identical to the one on the meter.

It worked fine with a multimeter. One thing to watch out for is that the wires are bare. The sensor is putting out a voltage all the time, so you don't want them to short. When it is sent to you, it has a cap over it to keep the voltage down to almost zero. Once you have it it would be worth soldering at least one of the bare wires into some kind of plug or socket to stop it shorting.

I ended up plugging mine into a labjack and just graphing it on a PC, but most people will probably want to move it around their tank a bit and see what the levels are. In any case, so long as you have a multimeter which can measure down to at least 0.2 mV , and you can multiply by 5 in your head, you will be fine.

Tim

 

[JDowns]

This is probably the route I'm going to go. Since labjack is open source it wouldn't be to difficult to customize a plugin to make the whole process of data logging and interpreting the data.

I don't see the problem with moving the sensor around the tank though? Sensor is wired to the labjack then to the pc via a usb, this shouldn't inhibit moving the sensor around the tank though. Only difference I can see in this scenario is that the labjack is wired to the pc, which shouldn't block mobility of the sensor. Unless I'm missing something obvious here.

 

[VaughnH]

It would be very nice to see a photo of what you get when you just buy the sensor. I'm having a hard time picturing the "bare wire" aspect of it. Also, is the filtering, or whatever method is used to make this a PAR sensor and not just a light sensor, in the sensor?

 

[SuperColey1]

Pictures for you H:

Midland Reefs Ltd :: Apogee...

AC

 

[JDowns]

From what I gather from Apogee's spec sheets the sensor is what is calibrated. The meter is just that, a conversion unit and a datalogger. A labjack should be able to take place of the meter.

 

[VaughnH]

Pictures for you H:

Midland*Reefs*Ltd*::*Apogee...

AC

Good! Thank you. I wonder if it is economical to buy a mV meter to be dedicated to the sensor, something I feel too lazy to look up for myself.

So, it is the stuff inside the sensor head that makes it measure PAR and not some other form of light intensity. That should trigger someone's creativity and result in something even better than the complete unit.

Sort of on topic: what does the screw in the back of the sensor do?

 

[JDowns]

I like the idea of the labjack. You could expand off of it with other sensors as long as you know the voltage outputs and have it all monitored on a pc. The open source environment really makes it appealling as well. You could monitor Temp, PH, O2, CO2, control lighting / dimmable also, water height, water spills, etc. Could be fun to play around with different things.

 

[JDowns]

Sort of on topic: what does the screw in the back of the sensor do?

I would think the screw is for mounting the optional leveling plate.

 

[Tom Barr]

I like the idea of the labjack. You could expand off of it with other sensors as long as you know the voltage outputs and have it all monitored on a pc. The open source environment really makes it appealling as well. You could monitor Temp, PH, O2, CO2, control lighting / dimmable also, water height, water spills, etc. Could be fun to play around with different things.

Ideally, it would be nice to have a simple all in one unit that is able to data logs and interface with graphing software automatically both fro control and monitoring.

pH
Redox
Temp
CO2
O2
light/timers/dimmers
water levels
Water spills
Feeders
Dosing
Automated water changer

Etc

Not much more than temp, CO2, dosing, light and water changers for 99% of folks in planted tanks.

So 5 main parameters.
You could use the probe to dial in the PAR you want, if you had a suspended bar and a small motor to raise and lower the light, then that could function as a dimmer as well.



Regards,
Tom Barr

 

[VaughnH]

I would think the screw is for mounting the optional leveling plate.

Yes, it does look like that is what it is for. Right now I have our local club's PAR meter, so I may get my nerve up and remove the screw to see if that is the case - it looks 99% certain. Then it will be easy to make a simple and rugged holder for the sensor to make it easier to take measurements at various locations in the tank.

 

[JDowns]

Since I"ve been dying to know what my par readings are I ordered a U3 Labjack and a quantum sensor.

Be interesting to see what levels these "highlight" plants are actually growing at, and not assuming I have low, med, or high light.

I'm more curious about my non CO2 tank than anything else, with PC lighting.

I'll also be able to measure some Tek fixtures.

 

[VaughnH]

The more PAR data we get, when it includes the lighting specs, the distance between the light and the sensor, and how the PAR varies as you move it around the tank, the more accurately we will be able to guess what any given light fixture will do on any other tank. So, be sure to get good data, and, PLEASE, report it here.

 

[JDowns]

Labjack will be here tomorrow so I can start playing with the software right away. I'm hoping the graphing doesn't take to much modification, but with Apogee's lead time for shipping (2-3 weeks), I'll have plenty of time to do any modifications.

It would be nice to have some type of graphed database.

At what par would be considered in a "rough" manner, low, medium, and high?

I'm assuming right now without seeing anything that the sensor will be outputing a constant reading through the meter (labjack). I'll probably have to have an output that I can view and a push button type device used to capture a logged output on a predetermined plot. This is going to take a little pre planning.

 

[JDowns]

To keep the contacts safe from water, I decided to enclose the Labjack in a hobby box, and add a viewing window of acrylic to view the LED status light. The USB cable hole was drilled and a rubber grommet was used to seal that port. Once the sensor arrives I'll do the same for that wire. Although I might use a quick disconnect type scenario. I'll have to make a trip to Radio Shack or Fry's Electronics and see what I can come up with since I like the idea of being able to easily disconnect a component and have the contacts water resistant.

Now that the unit is water resistant I'll start playing around the with software.

 

[JDowns]

The more PAR data we get, when it includes the lighting specs, the distance between the light and the sensor, and how the PAR varies as you move it around the tank, the more accurately we will be able to guess what any given light fixture will do on any other tank. So, be sure to get good data, and, PLEASE, report it here.

I absolutely agree and will post all findings.

Reason I ask what is considered low, medium and high par. Would be so we can graph accordingly. I would think a par spectrum if you will. Use a standard BGR spectrum. Blue being low par, Green being medium par, Yellow being high par. That would help differentiate zones. Then we can sort plants properly by PAR rather than WPG rules.

Now I understand there are many factors that can influence par. Covers / cleanliness, turbidity, surface agitation, tanins, reflectors, etc. But given the wide range of par plants adapt to, we should still have some wiggle room, but these factors have to be taken into account.

Plus as you have noted, the more data we can gather, the better understanding we can have for a given fixture, and the better understand we can gain.

 

[VaughnH]

PAR numbers are even more complicated than high, medium and low. PAR increases as you get closer to the light source. In fact for most relatively small dimension sources it varies inversely with the square of the distance. So, there is no one PAR number that characterizes what the light is providing for the plants. It can be 50 micromols at the substrate, 150 micromols half way up in the tank, and 250 at the surface. I think we are going to be stuck with considering just the substrate level PAR and the height of the fixture from the substrate (which then determines the PAR higher up in the tank.) Any other scheme seems to me to get so complicated no one could use it.

 

[JDowns]

I think it would be interesting to see what a daily / weekly cycle would look like as far as PH, O2, Redox, and temp. Maybe even TDS and Conductivity in the future along with CO2 (not jumping off the cliff just yet ).

How reliable are the nitrate probes? This would also be intriguing to guage uptake rates.

 

[JDowns]

The more PAR data we get, when it includes the lighting specs, the distance between the light and the sensor, and how the PAR varies as you move it around the tank, the more accurately we will be able to guess what any given light fixture will do on any other tank. So, be sure to get good data, and, PLEASE, report it here.

Can we agree on the parameters for testing. Where data is collected and how many spots. Obviously plant mass is going to cause some interference here. But if we have a standard, then we can database the findings better and create one thread with all the information.

I can test on my 150 all sorts of bulbs, Aquaflora, Midday, Aquablue, 10000k from Catalina, and in alot of configurations, from 80w to 480w. Then on the 29g biocubes the pc's.

At the lfs I can test a myriad of different fixtures. Everything from a few ADA fixtures with MH, Tek 4ft 4-bulb, Archea light fixtures for nanos in all sizes, and a few other fixtures they have up and running.

Sensor should be here tomorrow or Friday, so I planned to do some measurments over the weekend.