growlux bulbs

Hi Mick,
I guess we need to understand why you swapped bulbs in order to have proper context for your question. Was there something wrong with the original bulbs?

Grolux bulbs are pink, therefore if all you have over the tank are these bulbs then yeah, the tank will look pink. It's only OK if you like looking at weird pink tanks. If it makes you puke, then it's definitely NOT OK.

Click this link to have a read of the thread T8 Lighting up for renewal

Cheers,

OK, thanks for the clarification. Well, now you can be absolutely sure that spectrum is irrelevant and that it is folly to pay more money for bulbs that don't really improve growth performance. I advise to return to your original bulbs or to mix and match to suit your taste. Whatever you were reading was probably written by the Architect of The Matrix - or by someone who's life savings was used to purchase stock in The Grolux Corporation.

Cheers,

Hi all,

you can pair them with a 8.000-10.000k bulb

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This will work, "Grolux tubes" are fine as grow-lights, they have that funny pink look because they are producing a lot of their light in wave lengths that will be intercepted by "chlorophyll a", towards the red peak in the graph below (630 - 690 nm). LED horticultural grow lights are often just a mix of blue and red LED's to maximise "useful" light. The K values aren't a very useful measure, but you can mix the low K value of the growlight (3000K) with a bluer light (10000K) as Clonitza suggests to improve the look of the light.



cheers Darrel

clonitza said:

Ceg try to be open minded even on the other side ... you still haven't convinced me that two bulbs with different spectrum, let's say a pinky and an actinic, have the same PAR 🙂.

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Mike, as shown on the chart provided by Darrel, it's not really as simple as whether a bulb with a certain spectrum has more PAR. In fact, roughly speaking, the energy of radiation is directly proportional to it's frequency. What does that mean? It means that the higher the frequency of radiation, the higher the energy. Red light has the lowest frequency of all visible light. Do you see the color bar on Darrel's chart? Red is all the way on the right with the highest wavelength and the lowest frequency. Blue and indigo light is on the left with the lowest wavelength and the highest frequency. This means that indigo & violet light are THE most energetic radiation in the visible spectrum.

So on face value alone, blue, green and yellow light should have more PAR than red light. But it's not as simple as that. As the chart shows, it's not just which frequency has the highest energy, but it's also how the plant responds to the frequency. The chlorophyll chart shown above is a response curve. It shows how that particular chlorophyll molecule responds to light wavelengths.

The green curve shows that Chlorophyll-a has it's maximum activity both at around 430 nanometers, (deep in the blue) an it has an even better activity response at about 680 nanometers, which is deep into the red. Chlorophyll-b, (the orange curve) responds similarly. You can see that from cyan to orange these two pigments don't respond very well at all. You also see that any color from indigo to light blue and from yellow to medium red is used by these two pigments?

The Grolux bulbs only address the red area of the curve. In fact it's not even a certainty that the output of those bulbs are at the peak frequencies of either pigment. So they completely ignore the other parts of the response curve, sell pink bulbs, and claim that this is somehow "ideal".

Again, this isn't even close to the end of the story. People are quick to point out the low response that chlorophyll-a and -b have to the middle frequencies. But so what? These aren't the only pigments in the plants arsenal. In order to take advantage of the full spectrum throughout the photoperiod plants and algae have an array of pigment types which tailor their response curves to available light. These pigments capture the PAR that chlorophyll does not, and then passes the energy on to the chlorophyll complex. Pigments such as Carotenoids, Xanthophylls, Flavonoids all have responses which peak in the flat area of the curve shown above.

Therefore, it doesn't matter what spectrum of bulbs you have. Whatever spectrum you have, the plants will develop Auxiliary Pigments that are optimized for that spectrum, and which will then pass on the PAR energy to the Chlorophyll complex. You don't have to tailor your bulbs to plants needs because they adapt to what you provide. What you need to do is to avoid sending too much PAR energy to the tank because the plants have a limited ability to protect themselves from an overdose of PAR. The pigments used for "sun burn" protection are in the classes such as Phycocyanins, Allophycocyanins and Phycoerythrins. These pigments reflect energy away from the leaf in order to protect the plants.

Far from being a rigid rule about what color is necessary, plants simply use the various colors to regulate their metabolism. More sugars are produced under some frequencies, while amino acid and protein production increases under other frequencies. There is no advantage whatsoever in tailoring bulbs. This is what The Matrix wants you to think so that you will spend more money on specialist "Plant Bulbs". This is an illusion of the highest order.

Cheers,

Hi all,
I was going to answer a bit more fully when I had time, but it is all in Clive's post. Personally I would rather have a lamp with a higher colour temperature, mainly because of the increased energy of the "blue" photons that Clive alludes too, although this would be most relevant for deeper tanks.

I don't have a PAR meter, but I would be very surprised if the "Grolux" tubes chuck out more PAR than an equivalent wattage tri-phosphor 6500K tube.

cheers Darrel

Aha, excellent! Thanks for the clarification. It would be interesting to see the graph.

Cheers,

H all,

I have a plot somewhere I'll dig out that I took with a spectrometer on a grolux lamp and there are peaks at about 420nm and 465nm.

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I'd be interested in these as well.

I've found this PAR curve, but I don't know where it came from originally. Assuming it is correct, it should give you a better estimation of the absorption spectra of all the photosynthetic pigments.



There is a fairly old WWW page with links to the actual spectra for different lamps <http://members.misty.com/don/f-spec.html>, but unfortunately the images aren't available.

cheers Darrel

Hi all,

Sylvania GroLux Standard T12

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That is the sort of thing I had in mind. The Growlux spectrum does look a fairly good match for the PAR graph (although obviously with a much bigger "red" peak).

Personally I wouldn't buy the Grolux tubes specially, but the "Osram Lumilux 880 Skywhite + Sylvania Grolux" image (below) from "James' Planted Tank" does look a very attractive mix with a high CRI. http://www.theplantedtank.co.uk/

With apologies to James for the earlier "hot link".


cheers Darrel

Yeah, that's a nice plot and seems to cover all the bases. There is actually a fair amount of blue in there, but I'm with Darrel. As explained earlier, there is no need to use only Growlux. There are too many other nicer looking bulbs out there and the colors simply don't matter.

Having said that, if you have red plants or red fish and would like them to "pop" a little better then using Growlus or Triplus in combination with bluer/greener/yellower bulbs will compliment the colors better. Strictly an aesthetic affair.

Cheers,

Hi all,
Thanks Mike. An interesting read, and actually shows that if you don't mind the colour and are willing to pay a premium that "GroLux" is a reasonable choice of tube for a T8.
"Overall the bulb that achieves the best apparent match with the action spectrum is the original GroLux." View attachment 134790
Also

High performance fluorescent tubes are capable of generating the same, or even slightly more, light output per Watt than MH bulbs....... Considering that these inexpensive T8 bulbs can be overdriven by electronic ballasts with high ballast factors (> 1), thus delivering even more light, they are possibly the best option to light a planted aquarium in terms of performance/cost factor.

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The overall "best" T8 tube in the review was an ordinary 5000K tube: "Philips Advantage T8 lamp - F25T8 ADV850 ALTO"

cheers Darrel

dw1305 said:

actually shows that if you don't mind the colour and are willing to pay a premium that "GroLux" is a reasonable choice of tube for a T8.
"Overall the bulb that achieves the best apparent match with the action spectrum is the original GroLux."

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We ought not to lose track of the lesson learned and the point made painfully obvious to the OP. We really need to distance ourselves from the concept of "best bulb". The fact is that the OP discovered that the color of this "best bulb" was absolutely hideous and that the premium pricing of the bulb was unreasonable. This is a double whammy which has little redeeming value.

Let's also not forget the point that because of physiological adaptation, the plants do not really care about their supplied spectrum, as well as the fact that most peoples algae problems can be traced directly to their irrational use of too much PAR. We can see that there is no reason to get any of these bulbs other than for reasons of how the viewer responds emotionally to their colors.

I would caution everyone to avoid being so tunnel visioned that we miss the big picture. We are trying to maximize plant health, which is a function of many more things than how much PAR we can stuff into the tank due to some absurdly overpriced light bulb. In case anyone hasn't realized it by now, chasing high spectral energies, introduce by these very same bulbs, is the fundamental root of many of the our tanks' problems, NOT the path to their salvation.

Cheers,