knna

When comparing bulbs efficacy for MJ grow, we colide with no quantum yield curve avalaible for cannabis. So I do one aproximation, i think the best without lab equipment.

I used a article about detecting MJ fields from sky (planes/sat) of Us gv to build a curve of MJ absorbance of each wavelenght. Please note its a average curve, since absorbance change a little between strains and stage of development. The reference strain in Colombian Sativa, and a little increase in absorbance of yellow and decrease in blue is expected in advanced bloomery stage.

The result is a very flat curve, wich explain why HPS works so well for cannabis.

There is not a photosyntesis action curve for cannabis, but its supposed little differences between species, so using the Inada average curve for 26 herbs plants, wich includes similar environment to cannabis plants, will give a good aproximation.

Matching both curves i obtained the quantum yield curve of cannabis. Its refered to photosyntetic action of light, no give information about other effects of light.

The result is in adimensional measure, given in percentage of max photosyntetic effect (i would like to measure mols of O2 produced at same mols of photons of each wavelenght, any lend me a lab? ). As a reference, in botany its known about 14 mols of HPS light is neccesary to obtain 1 mol of O2 (and 13 for CW fluo). The max eff is about 10 (for a 667nm LD with a 20nm bandwith), very near the theoretical max, so we can equipare the 100% rating of the graph to 0,1 (mols O2/photons) (the half point is obviously 0,05). But this only make sense if using irradiance (flux), not radiance (bulbs emision). Because of that, i let the graph as percentage.

The graph's blue line is absorbance curve. Red curve is the Inada one. Yellow curve is Quantum Yield curve (absorbance X action spectrum). Light blue curve is QY corrected for the relative energy of photons (700nm is choosen arbitrary like 1), we need it if the bulb spectral distribution is given in mW (usually). Using QY corrected dont provide any scale, its pure adimensional (so using 400nm as 1 result in a very dif curve), but give valuable info when comparing spectral distribution of dif bulbs.

Peace

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penguin

Hi knna

Welcome to HC.com!

That's a really excellent piece of work! Thanks for posting.


penguin

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FredFarts

So let me ask you this, Are 1000 watt HPS hortalux bulbs worth the xtra cash over the Lumalux 1000?

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"Being a Man means getting up one more time than they knock you down"
John Wayne

knna

I dont know if it worth the extra cash. Its dependent of personal preference.

I can help you on study the perfomance of each lamp. A 1% more efficiency (about 3% more light) worth? It all things are optimized, it translate to 2% more yield. Its cuestion of each grower decide what to buy.

Sincerelly, i think that "special for plants" lamps work better but very often the price difference is quite larger than perfomance difference. But its just my personal point of view.

I didnt study 1000watts lamps (i dont use it), but you can do it easily. Check my signature, there is a sheet to compute bulbs perfomance, knowing its power comsuption, spectral distribution and lm output.

Hope you like the sheet.

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