# PAR....Connecting the dots



## digital_gods (Apr 23, 2010)

Now that we have all the par data of all the club members tanks, we can get a better idea of what light requirements are needed for each tank and a idea of par requirements for different plants. I got some clippings that are from Coral & Reef USA - 2012 Annual to help us Brain Storm a better guide for aquatic plants. I got an ad from AquaticLife that actually give a lot of information in a info graphic format. They give us the tank footprint, corresponding lights they have available and what can be housed in the tank based off tank height. Next clipping is a chart of corals par requirements in a grouped form. I think this is be a great idea to come up with something similar for plants. The last clipping is just to show par at different level in the tank and the placement of different corals groups in a tank based on par and tank depth. I think is would be great to come up with something similar that is applied to aquatic plants that would give visual explanation of how much light is loss in aquarium.

--Robert


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## Michael (Jul 20, 2010)

These kinds of charts and recommendations for PAR levels in the species accounts in the Plant Finder are what I hope will come out of this. But at this stage we need a lot more data.

So, members, borrow the PAR meter and post your results! Right now the meter is available.


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## Newt (Apr 1, 2004)

This is a nice project you guys and gals are working on. PAR is more useful info but still has draw backs. PAR does not differentiate the wavelenth (color)of light as does PUR (this also has draw backs)

A few facts to keep in mind while evaluating your data:

As light passes through water the intensity decreases. The shorter wavelength blue light penetrates water better and more quickly than red, which is slower and absorbed more quickly. Chlorophyll, the photosynthetic pigment used by plants traps blue and red light but is more efficient with red light. Blue is used at the same rate as red - one photon of either red or blue produces the same amount of photosynthetic action.


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## digital_gods (Apr 23, 2010)

The most accurate way of determining the necessary par per plant would to use a Junior PAM http://Walz.com/products/chl_p700/junior-pam/introduction.html. This little device does it all except french fries for low low price of $3300.


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## fishyjoe24 (May 18, 2010)

digital_gods said:


> The most accurate way of determining the necessary par per plant would to use a Junior PAM http://Walz.com/products/chl_p700/junior-pam/introduction.html. This little device does it all except french fries for low low price of $3300.


isn't foreverknight jason building something like that but for much cheaper?


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## foreverknight (Jul 8, 2010)

nope joey i'm building a spectrometer that allows you to get a general measurement of the intensity of the different colors of light being produced by any one source


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## Newt (Apr 1, 2004)

foreverknight said:


> nope joey i'm building a spectrometer that allows you to get a general measurement of the intensity of the different colors of light being produced by any one source


Thats the way to go. You going to make normalized spectral output graphs?


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## foreverknight (Jul 8, 2010)

that is the plan to an extent newt I found this article on the internet and a project group that has made them and a program to interpret the data. here is the link just for you and anyone else interested. If anyone would like to build one themselves i can help with the build. after I get the build done i will work on seeing if the program works on windows computers it says it should but those of you with mac and linux experience will be ready to go. I'm personally a little behind on my mac and linux work lol.

here is the link
http://publiclaboratory.org/wiki/video-spectrometer-construction

p.s. after i get done with this out of water version i will be trying to adapt the design for aquatic use.


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## Michael (Jul 20, 2010)

I understand the differential absorbtion of the red and blue wavelenghts as depth increases. But since a PAR meter measures total photosynthetically active radiation, how does this make it less accurate than a spectrometer for our purposes?


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## foreverknight (Jul 8, 2010)

the led issue is one of them but hope to have that solved really soon....


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## Newt (Apr 1, 2004)

Michael said:


> I understand the differential absorbtion of the red and blue wavelenghts as depth increases. But since a PAR meter measures total photosynthetically active radiation, how does this make it less accurate than a spectrometer for our purposes?


The problem with PAR is that it includes all light in the visible spctrum including green which doesnt do much for photosynthesis. You also wont know which bulb has a better output in the red or blue - it doesnt differentiate. So you could have a bulb thats strong in the green and weak in R/B and another bulb that has has good blue poor red and average green and yet another bulb that that has strong red and meduim blue and green -they could all fall rather close on a PAR meter. PUR is more important but still doesnt differentiate R/B.

By having a normalized plot you know which bulb puts out where along the spectrum and how strong. Thats how I know my T8s blow away all CFs.


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## Michael (Jul 20, 2010)

Actually, our meter (Apogee MQ-200) does not do that. It has a peak spectral response between 400 to 700 nanometers. The spectral response graph for the meter closely approximates the plant spectral response graph. It does not measure all light in the visible spectrum from 300 to 800 nanometers.


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## Newt (Apr 1, 2004)

Visible light is 400nm to 700nm for the human eye (perhaps a tad outside each end for some).


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## fishyjoe24 (May 18, 2010)

that's why we need something like what jason is building..


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## Michael (Jul 20, 2010)

I stand corrected.


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## foreverknight (Jul 8, 2010)

can everyone believe out of all the stuff i have here at the house i don't have a hot glue gun i can't believe it... will be getting one today and some sticks so i can start finishing the project.. i have everything i need just need to put it together and get the program up and going


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## wwh2694 (Aug 15, 2008)

Ok i finally got the Par data of my tanks.
ADA 60H tank with fishneedit MH 75watts: Bulb 9months old
Top water 8 inches 442.
Substrate 23 inches 72. Sides 64.
Middline tank 16 inches 80.

ADA 120H tank with 2 ADA solar 1 MH 150watts each: Bulb 9months old
Top water 10 inches 300.
Substrate 29inches 120. Sides 110
Middline tank 20in 140.

Its weird coz the difference of the 2 lights brands is huge. My fishneedit light has 442 only 75w but all the way to the subtrate its big drop 72. Now my ADA lights 2 150w its only 300 on each but the substrate is consistent for 110 to 140. Never went down less than 100 probably because it has 2 mh bulb. I will try to one and give the result.


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## wwh2694 (Aug 15, 2008)

Ok i tried running one ADA solar light on 1/2 of my 120h tank.

Top water 10in 300.
Substrate 29in 100 avg. around half of the tank.

I will try to get a new bulb for these light and let you all know the readings.


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## foreverknight (Jul 8, 2010)

it has to do with the color spectrum that is getting to the substrate... it is how the different colors of light as filtered out through the water.

also after i finish the one i am constructing now i will be attempting to make a waterproof version. but only after i get the current version up and running with collaboration from Robert Bradbury. hopefully with the water proof version we can show how the depth of the water affects the various wavelengths of light and where we need to increase those for photosynthesis without breaking the bank and raise awareness on what is actually happening in our tank waters with lighting.

like the saying says seeing is believing.


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## foreverknight (Jul 8, 2010)

i want to ask texgal and others this question and it goes along with everything else in this discussion... when i get the spectrometer made do you think we could make a sticky so pictures of the wave forms could be posted and easy reference.


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## Newt (Apr 1, 2004)

Good luck.
I'm interested in the LED data your spectrometer shows. Of course it will vary from bulb to build to mfg to mfg


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## foreverknight (Jul 8, 2010)

and that in itself is why i am doing it newt


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## Newt (Apr 1, 2004)

Good on you!


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