I just objected to the somewhat abstract and sweeping generalization “spectrum doesn't mater”, and I went about trying to qualify that statement. Which I hope I’ve/we’ve now done.
Hi Troi,
This generalization is, in my opinion, a much better way to think about lighting because in order to consider relevance, one has to in effect take the factor being studied into consideration in terms of how one will execute their processes. So you have to ask yourself, what type of bulb will I need to restrict myself to, or what bulbs must I now avoid due to their lack of performance. In the real world, the answers are: No restrictions and No avoidance. The reason being that none of the bulbs in question have a marked improvement over any other bulb. Therefore, within the context of our tanks, there is no relevance because there is no bulb you can buy that does not have sufficient blue and red.
So lets take a look at some of the hypotheses you offer which might have relevance:
However, many demanding plants for instance Hemianthus callitrichoides ''Cuba'' require high light and high CO2 etc to thrive.
No, this is not true. I and many others can and have grown HC with low-to-middling light. That HC requires high light is another construct of The Matrix. People think that they need high light because they were told this. So they add lots of light, do not pay attention to flow and CO2, and the result is meltdown. While there is little doubt that HC has a higher light compensation point than say, Ferns, the LCP for HC is not very much higher than it is for Ferns. Even if it's 100% higher that just means that a Fern will grow at PAR levels above 10 micromoles and that HC will grow at levels above 20 micromoles. This is not very high at all. But no one uses 20 micromoles. It's just too dim aesthetically, and the HC will take forever to grow.
I think people mistake growth rate with health. You can throw tons of PAR at a plant and it will grow faster. We already know that. So, if HC is grown at a PAR of 100micromoles, and if flow/distribution and CO2 is adequate the plant will look lush and beautiful very quickly. If the same plant is grown at a PAR which is just above LCP then it will take a very long time to reach that lush state - but it will get there eventually, and it will be just as healthy. But no one wants to wait forever, so they pummel the plant with high light and THAT'S WHY there is so much failure with HC. I don't have ANY trouble growing this plant at low lighting levels. George Farmer has no difficulty, Dan Crawford, Mark Evans and Tom Barr have grown this plant at low lighting levels. It's only the Megawatt Loving Klingons (MLK) who have difficulties with HC. Also, as mentioned by George, there has been no perceptible differences in growth rates or in health based on the various fluorescent bulbs used. I've used standard office bulbs and even splurged for Grolux (which are high in Red and Blue) George likes fancy bulbs but he has also used cheap bulbs without difficulties.
Oh, and by the way, those fancy ADA bulbs? It turns out that they are very high in green, and it turns out that their ballasts produce 2X-3X less PAR than other ballast. When you see those fantastic Amano gallery shots, the lighting used to take the photography might be high but the plants are actually grown under low lighting. In the flesh the tanks look bright because the human visual cortex has it's response peak in the green. So here is an entire industry centered around a color band that has the lowest performance according to the article. Does it matter one iota to their ability to produce amazing tanks? No!
Regardless, I think though from our point of view it would perhaps be interesting to consider that the compact and bushy growth that many of us find attractive is largely due to the red part of the spectrum, as implied by the experiments results.
No, this is not worth considering either. Compact and bushy growth is a function of the ability of the plant to rid itself of the gaseous hormone ethylene. This is yet another myth. This is specifically WHY I continue to harp on the importance of flow and distribution. But people don't really want to hear about that because it's another difficult concept to grasp, so it's easier to talk about spectrum.
I am sure that there are many that have failed due to inadequate light intensity as well
No, the people who report this only THINK that they failed due to low lighting. They simply did not understand the truth. I think you're forgetting that we collectively have the empirical data, not only in our own tanks, but in tanks around the world where people ask our opinion and we provide instructions on which factors to ignore and which to pay attention to, and we have a pretty good success rate, so we constantly see the results, which reinforces what we understand to be the truth. Is there a possibility that there are other factors we do not yet understand? Absolutely! But one thing is for sure, it's very easy to disprove a theory, and this theory of how spectrum is significant to the way we grow is very easy to disprove.
I’m well aware that photosynthesis is a quantum process, but I’m also aware that although modern science has become very technical it is still possible to describe it in a way that people without scientific training can understand. To be frank I’m very scientifically trained and I had difficulty understanding your explanation of PAR.
Most likely there are two factors in the inability to grasp. The first might be that there is a preconceived idea about what light itself is and that conflicts with the preconception. Another contributing factor might be that there is a lack of understanding about how plants actually use light. Let me offer this as a clue:
When God said "Let there be Light" he did not mean "Let there be a lamp switch that folks can flip it so that light will enter their dark room". What he meant was "Let there be a reality and a Universe whose very construct is based on the properties of light as it's fundamental participles of existence". It turns out that we are actually the servants and the children of light.
So, in now way am I dismissing the importance of spectrum and in no way have I implied that there is no relevance to spectrum. What I have stated is that the things that we are using to measure the importance of colors in our tanks is of little value and is in no way indicative of the importance of color, and that using the bulbs we have at our disposal, the effects of color are not to be seen in our tanks in the same way as that demonstrated in that experiment.
I have not denigrated the ability of the professors or of the journal in any way. What I have said is that their focus and priorities will not necessarily match our priorities and so it is important to understand the context of the article. Even though we learn something, the data may not apply to us.
We should be feeling liberated about this. We should not be pensive. We can use colors in any manner we chose without fear of ill health. I love playing with colors and seeing their aesthetic effects on the tank and the fish. We should view the spectrum as a way of enhancing the aesthetic appeal of the tank and we need not handcuff ourselves thinking about what colors we can or should use just because it is less than "optimal".
Cheers,
I'm very tempted to suggest that I would splurge my, not so hard earned, cash on special growth bulbs just to be contentious. Especially since the evidence that I've unearthed overwhelmingly supports my supposition that spectrum matters, and maybe, just maybe, they might provide additional benefit to the type of growth we find attractive
