PAR meter Group Buy (1 Viewer)

[melev]

Mods, I don't know what forum to put this in, so feel free to move it...

Guys, Reefcast is organizing a group buy for PAR meters. If you've thought about buying one but thought it was too expensive, how does 40% off sound?! That got your attention, right? The QMSS-E meter retails for $249, but with this nationwide Group Buy, you can finally get one for $149. All the details are here:

http://reefcast.com/groupbuy.php

Reefcast will NOT be collecting any funds. All payment will be made to Apogee directly when it is time. We are just organizing it to save you money.

We are trying to get the word out to as many hobbyists as possible.

 

[crvz]

I don't see any harm with it here, Marc, but maybe I'll get over-ruled. I just joined the list!

 

[slyfox]

very nice idea

 

[hank]

This was on our local forum too. Here's what a friend of mine has to say:

"That's a good deal, it is just a shame that the Apogee sensors have such a poor spectral response over the wavelengths that define PAR (400 to 700nm). Apogee uses a gallium arsenide photodiode (GaAsP) as the detector. GaAsP underestimate the blue end of the PAR spectrum, because they have a poor blue light response (i.e. a quanta of blue light doesn't induce as much current as a quanta of red light).

Whether the sensor uses a silicone detector (good blue light response and what is used in more expensive sensors, like the Kipp & Zonnen PAR-Lite and LICOR quantum sensor) or a GaAsP, the detector responds to a broad range of wavelengths. To make it a PAR sensor, optical cutoff filters are used to block light with a wavelength shorter than 400nm and longer than 700nm. To keep cost down (Apogee is one of the least expensive PAR sensors on the market) Apogee uses a cheaper cutoff filter at the 700nm mark, that means the sensor picks up a lot of light with wavelengths over 700nm (which is light that doesn't drive photosynthesis).

Your ideal PAR sensor has a even spectral response over the entire range of wavelengths between 400 and 700nm, with sharp cut offs at the ends. If you plot relative response over wavelength, the ideal sensor's response would look like a box. The Apogee sensor's response looks more like a hill with its peak centered somewhere between 650 and 680nm, and trailing off past 700nm.

The above may not mean much to a lot of people, but I come from a plant physiology lab and so PAR is pretty important to me.

Jay"

 

[crvz]

Hank,

Good words, but honestly, as long as it measures consistently over time who cares how precise it is for actual PAR value? All the numbers are relative, and I figure most folks are going to use this device to determine PAR drop over time with lighting, right? I've never seen someone go as far as to say "this coral needs a PAR range within ...", but I'm not sure if they do that with plants either.

 

[hank]

"this coral needs a PAR range within ..." I think if you went to public/ research aquaria then that actually might be more like the case, but otherwise I see your point. Though wouldn't that be helpful if everyone had one for on a site like DFS?!

For comparing your own bulbs this thing is probably perfect, as long as you don't change bulbs.

The problem is that you do get comparisons among hobbyists and with the apogee's shortcomings in reading different wavelengths' PAR equally, someone may claim superiority when that is not actually the case. I think you can imagine the rest of the story I have in mind... we don't always follow the scientific method as hobbyists. Either way, I think it is worthwhile to consider his comments.

 

[SnMan]

I am on the list too. Thanks Marc for the heads up.

 

[stdreb27]

"this coral needs a PAR range within ..." I think if you went to public/ research aquaria then that actually might be more like the case, but otherwise I see your point. Though wouldn't that be helpful if everyone had one for on a site like DFS?!

For comparing your own bulbs this thing is probably perfect, as long as you don't change bulbs.

The problem is that you do get comparisons among hobbyists and with the apogee's shortcomings in reading different wavelengths' PAR equally, someone may claim superiority when that is not actually the case. I think you can imagine the rest of the story I have in mind... we don't always follow the scientific method as hobbyists. Either way, I think it is worthwhile to consider his comments.

You can make 1 mean whatever you want it to mean as long as it is uniform across the board. So in a general hobbiests tank it really wouldn't matter... Since his tank is across the board for him...

 

[hank]

"this coral needs a PAR range within ..." I think if you went to public/ research aquaria then that actually might be more like the case, but otherwise I see your point. Though wouldn't that be helpful if everyone had one for on a site like DFS?!

For comparing your own bulbs this thing is probably perfect, as long as you don't change bulbs.

The problem is that you do get comparisons among hobbyists and with the apogee's shortcomings in reading different wavelengths' PAR equally, someone may claim superiority when that is not actually the case. I think you can imagine the rest of the story I have in mind... we don't always follow the scientific method as hobbyists. Either way, I think it is worthwhile to consider his comments.

You can make 1 mean whatever you want it to mean as long as it is uniform across the board. So in a general hobbiests tank it really wouldn't matter... Since his tank is across the board for him...

That's the point: they aren't.

They read the red spectrum higher and even that which does not assist photosynthesis therefore someone who has an entirely 650nm lighting setup is going to have a better reading than someone who has an actually better setup that focuses on the type of light we actually need. Don't get me wrong, this has its purpose for the price, but I am telling you that I don't think hobbyists should take this piece of equipment and consider it lab-grade to make decisions about bulb TYPE, and COLOR changes, rather than just to see if bulbs are wearing out.

Just take readings with a grain of salt. (-water haha)

 

[Guest]

Hey Marc, can we get a discount on the QMSW-SS model in this group buy?

 

[stdreb27]

"this coral needs a PAR range within ..." I think if you went to public/ research aquaria then that actually might be more like the case, but otherwise I see your point. Though wouldn't that be helpful if everyone had one for on a site like DFS?!

For comparing your own bulbs this thing is probably perfect, as long as you don't change bulbs.

The problem is that you do get comparisons among hobbyists and with the apogee's shortcomings in reading different wavelengths' PAR equally, someone may claim superiority when that is not actually the case. I think you can imagine the rest of the story I have in mind... we don't always follow the scientific method as hobbyists. Either way, I think it is worthwhile to consider his comments.

You can make 1 mean whatever you want it to mean as long as it is uniform across the board. So in a general hobbiests tank it really wouldn't matter... Since his tank is across the board for him...

That's the point: they aren't.

They read the red spectrum higher and even that which does not assist photosynthesis therefore someone who has an entirely 650nm lighting setup is going to have a better reading than someone who has an actually better setup that focuses on the type of light we actually need. Don't get me wrong, this has its purpose for the price, but I am telling you that I don't think hobbyists should take this piece of equipment and consider it lab-grade to make decisions about bulb TYPE, and COLOR changes, rather than just to see if bulbs are wearing out.

Just take readings with a grain of salt. (-water haha)

yeah, I guess I was thinking how I would use it. As a measure to see if my bulbs are going out. The par value that corals need I know absolutely nothing about.

 

[lesd]

This article might help if you're concerned about the accuracy of the Apogee meter:

http://www.advancedaquarist.com/2005/7/review/view

-- Les

 

[melev]

Hey Marc, can we get a discount on the QMSW-SS model in this group buy?

Yes, you can choose any model you like from their site. We are simply recommending the QMSS-E so as we trade information with one another, the numbers compare nicely.

Hank, I just read some of your posts. Here's what I'm thinking:

I just heard Sanjay's presentation at CRASE on Saturday, and he discussed the various meters. For what we are doing with our tanks, the higher end meters are simply not required. Sanjay showed us two kinds that he'd like to get one day, both of which are $1000 each, roughly. Ouch. He did say the Apogee is fine, and even mentioned my GB to the audience. I don't even know who told him. LOL

For what we are trying to learn, this one should do the job. Will it do well in a tank only lit with 20,000K bulbs? That may be questionable, but I did test the light coming out of a 400w 20,000K bulb earlier this year and the meter seemed to do well consistently with all the tests I put it through during a two week period. The majority of us just need some type of guideline to get an idea of what our tanks are getting and how our bulbs are holding up over a period of time. I feel this meter will do the job adequately.

Apogee is coming out with a new meter soon (I've seen the PDF), but it isn't on their site yet. It costs $349, but will store up to 99 measurements, which can be downloaded via USB to a computer later. It can be set to measure 30 minute increments up to 99 times in a row. That would be very useful in a greenhouse, but not so much for what we do. It should be on the market in about two months time.

-----

Check your emails for instruction. If you've not gotten involved yet, this is the final week to do so. All the details are on www.reefcast.com/groupbuy.php with a link to how to purchase them this week.

 

[melev]

I don't think hobbyists should take this piece of equipment and consider it lab-grade to make decisions about bulb TYPE, and COLOR changes, rather than just to see if bulbs are wearing out.

When I did my measurements, that thought never even entered my mind. I choose color of bulbs based on my personal preferences, not what a meter tells me. However, I can tell - with this meter - how my reflectors are doing and if my corals are getting sufficient light or not. And that is the whole point, to take the guesswork out how much light is getting into our tanks.