PO4 probe and par meter
- Thread starter LISound
- Start date
In a nutshell, a layman's explanation would be that a PAR meter's readings include the total light intensity for the the full set of frequencies (colors) of light that used in photosynthesis - precisely the frequencies that we are interested in measuring. A Lux meter, on the other, typically provides the total light intensity for a small range of frequencies. Typically they measure the normal "daylight" frequencies pretty well, as they are - by design - skewed to measure light perceived by the human eye. But as Greg indicated above, his Lux meter does not measure blue frequencies. And many of us - myself included - are very interested in getting a reading on that light also.
Obi-dad
Active member
To be precise, PAR meters measure more of the frequencies we want to measure than the Lux meters, but they also have a 'response curve' that under-represents blue and some of the red. If you go to the Apogee website (one of the popular PAR meters used in the hobby), you can see a graph of the response curve. Apogee response curve In that graph the blue and violet are in the 400-450nm wavelength range, and the red is at the 700 end.
The net result is you get a better reading from the PAR meter than the Lux meter, but whether you need a PAR meter or lux meter depends on what you want it for. If you just want to tell when to replace your bulbs due to declining output, you can use a Lux meter (much less expensive).
The net result is you get a better reading from the PAR meter than the Lux meter, but whether you need a PAR meter or lux meter depends on what you want it for. If you just want to tell when to replace your bulbs due to declining output, you can use a Lux meter (much less expensive).
Wheel of Time
New member
Scolley, I have not done any real research into a lux meter, but you and Obi-dad seem to know quite a bit. How much are a few of the ones worth purchasing. Forget about the real high-end as Im sure that is way more than we/I want to spend. Do you have a sense of 2-3 different reliable brands/models and price ranges to compare?
po4 probe would be handy too. Im still low tech using mostly test kits (do have the ph and temp probes though, but still no controller). I am tiring of test kits... I need to just bite the bullet and get a controller!
po4 probe would be handy too. Im still low tech using mostly test kits (do have the ph and temp probes though, but still no controller). I am tiring of test kits... I need to just bite the bullet and get a controller!
Well, I'm not the most informed. But as I understand it, cheap lux meters are dirt cheap, as has been stated here. But you can't get them wet. They are suitable for telling you when to change your lights. Personally I've got no interest in those.
I'm personally interested in at least a submersible lux meter - where you can measure how much light is in a particular spot in in your tank is getting. Those appoach $100, but they have the 'not measuring all the light' problem. The same submersible capacity in a par meter is a bit north os $300.
Or at least that's how I understand it.
I'm personally interested in at least a submersible lux meter - where you can measure how much light is in a particular spot in in your tank is getting. Those appoach $100, but they have the 'not measuring all the light' problem. The same submersible capacity in a par meter is a bit north os $300.
Or at least that's how I understand it.
terahz
1x10^12 Hz
I have a foot candle meter if anyone wants to use it just let me know. It looks like this:
manual: http://www.hydrofarm.com/downloads/fc/17911_LG17000.pdf
It is not for underwater measurements, but I'm sure if you put it in a Ziploc bag it will be fine.
manual: http://www.hydrofarm.com/downloads/fc/17911_LG17000.pdf
It is not for underwater measurements, but I'm sure if you put it in a Ziploc bag it will be fine.
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