Ny version av ljuskalkylatorn online

Kommentarer

2010-02-01 15:43:22.0

Du råkar inte känna till någon källa för lite riktmärken kring lämpliga värden för t ex en "ljuskrävande" bottentäckare. Eller andra växter. Eller mer generellt vilka värden man kan/bör röra sig inom.

Nils (Lingonfil)

2010-02-01 19:11:26.0

Jag tror Tom Barr brukar rekommendera att man lägger sig på runt 40 PAR om man vill ha sakta tillväxt men samtidigt klara de svåraste bottentäckarna, tex HC. Tror inte man vill gå under det.

deffen

2010-02-04 10:28:03.0

Hi Daniel, Thank you for the awesome light calculator that you developed and thank you to have published it.
The spectrum that you considered to calculate the PUR seems to consider only chlorophyll and not the other pigments of the plants.
I think that it's more realistic to consider the curves that is the result of the Elgersma experiments (Philips 1982)
You can find this spectrum, for example, here at page 7:
http://www.jbl.de/dl_documents/uk/uk_WWW7.pdf
Here are shown the spectrums of the various pigments of the plants that play a role in the photosynthesis:
http://www.aquagarden.it/articoli/41_pigmenti/05.gif

Best Regards

Claudio Cappelletti http://claudiocappelletti.blogspot.com

2010-02-04 12:32:30.0

Hi Claudio, thanks for the feedback. As you can see you can add whatever action-spectrum you think is fit for your plants.

But I must say that JBL have a completely different action spectrum compared to almost all other sources for plant action spectrums you can find references to on the internet:
http://www.google.se/search?rlz=1C1GGLS_svSE300SE356&sourceid=chrome&ie=UTF-8&q=photosynthesis+action+spectrum

The action spectrum I use have been measured up by exposing the underwater plant Elodea to all the different wavelenghts and then measured the oxygen produced.

I will go as far as say that the JBL-action spectrum is wrong. Plants are *very* sensitive to blue light and you can see the explosion of oxygen if you use completely blue light.

Blue light also have the advantage over red light in that it is not attenuated as much in water as red light.

Accessory pigments are associated with less efficiency for the plant so I would not trust accessory pigments for robust and fast growth.

Daniel Larsson

2010-02-04 12:41:17.0

Note to myself: Add the JBL action spectrum to my calculator when I come home from work..

Daniel Larsson

2010-02-04 15:20:03.0

Hi Daniel, the spectrum that I have shown it's the same that was present on the old Dennerle web site (now there is no more the spectrum of the lamps that they sell) and it's the result of the experiments that Elgersma made for Philips (not for JBL). The Philips Aquarelle was developed trusting this spectrum. If I remember well this spectrum was calculated from the oxygen production of various aquatic plants and it's the average of the results.
But also the spectrum that you used to calculate the PUR is widely used as you shown from Google and it's the one trusted to develop lamps as grow-lux.
The blue light penetrate better than red light in the pure water but if in the water there is some organic pollution the blue light is attenuated a lot by this and the red light it's not attenuated a lot by only 30-40cm of water in our tanks.
Plants generally prefer red light not blue light, the NASA has made some experiments to optimize the growth of the plants in the space and the results was that the best was to use about 92% red LED and 8% of blue LED (so they suggest to use both blue and red light but more red light)
http://www.goarticles.com/cgi-bin/showa.cgi?C=40280
If we have the same energy in the blue or in the red in the blue we are considering less photons with higher energy and in the red more photons with lower energy. As I know for the photosynthesis what matter is the number and not the energy of the photons so it's better to use red light (the PAR consider the moles of photons and so the numbers of photons not the energy of the photons)
That is why in Germany the hobbyst in the past used 2700-3000K lights like Philips (or Osram) 827 and 830. Now I think that most hobbysts prefer 6500K lights because this lights gives a better look to the tank (for human eyes) and the result for plants grow it's only a little worse.

I'm only trying to understand surely I may be wrong ;)

Thank you for your answer

Best Regards

Claudio Cappelletti http://htto://claudiocappelletti.blogspot.com

2010-02-04 15:29:19.0

I appreciated a lot that you calculated the PAR and that you have also measured this value directly with and instrument; and also the video that you have shown on youtube with the measured PAR in various points of your tank.

Thank you very much

Claudio Cappelletti http://htto://claudiocappelletti.blogspot.com

2010-02-04 17:37:14.0

http://www.webalice.it/ccappelletti78/blog/ELGERSMA.jpg
http://www.webalice.it/ccappelletti78/blog/PAR.gif
Elgersma spectrum and PAR are very similar so I think that the PAR efficiency may be the best index

The spectrums of the JBL solar, Giesemann midday and Narva bio vital are quite similar.... I think that all these tubes may be produced by Narva. (there are only small differences to adjust the color temperature)

Your data it's very very interesting thank you for the time that you used to develop the web application and to to gather the data.

Best Regards

Claudio Cappelletti

2010-02-04 18:07:15.0

Since PAR is just a little bit wider than the photooptic curve and almost looks like the action spectrum you prefer, why not use Lux/lumens instead of PAR?

There is a flaw with an action spectrum that holds back on blue, and I've seen it with my own eyes. Blue light trigger photosynthesis harder than red.

Here is a pdf (unfortunately in Swedish) that shows a picture on the second page where you can see how different colored LED:s triggers different kind of growth. It shows clearly that blue is much better than red:
http://tillvaxtprogram.slu.se/uploads/hartmut/InfoHartmut20090501.pdf

I think the NASA-citation is wrong, and I have seen it before. I think it should be the other way around - 92% blue and 8% red. I base this on the fact that blue light triggers stomatal opening (more available CO2) and that plants reflect alot of green/yellow and red. But almost no blue light at all.

Infact. I think this picture depicts how much light is reflected back from a plant - not how much light is absorbed by it: http://www.webalice.it/ccappelletti78/blog/ELGERSMA.jpg

Daniel Larsson

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