Wpg And Colour Temp

[craynerd]

I posted this in another thread but wanted to make it a topic of its own so i can hear more views!

Andywg said something a few weeks back in TFF chat and it got me thinking. All this talk about wpg is pretty pointless since does it not all boil down to the colour temperature as priority and then wattage / intensity at that colour temp? For example if i had 5wpg but all in the blue spectrum i would surely have less growth than someone at 2wpg but with a more balanced colour temperature.

Therefore instead of talking about wpg should we not start to incorperate the colour temperature and wave spectrum of which the light gives.

I mean has anyone come up with a forumula for optimum growth that incorperates these two factors. Like i said, it would be interesting to see who would get more growth, someone at 1wpg but with a colour temp suiting plants or someone with high wpg but say with the same colour temp (i.e using a few tubes!)


Chris

 

[Tempestuousfury]

Seems like a good q to me, though I can't say know much about plants...

However, generally the fluorescent bulbs I see are broad spectrum with high red and blue peaks and usually a small green one (on the graphs). So, going by what little I learned about this in AP Bio, since whatever the two chlorophyll types are, they generally absorb these frequencies, so wouldn't the wpg be the primary factor for these bulbs?

 

[Luke_e]

I'm afriad i'm way out of my depth here, but it should make an interesting topic.

 

[craynerd]

Seems like a good q to me, though I can't say know much about plants...

However, generally the fluorescent bulbs I see are broad spectrum with high red and blue peaks and usually a small green one (on the graphs). So, going by what little I learned about this in AP Bio, since whatever the two chlorophyll types are, they generally absorb these frequencies, so wouldn't the wpg be the primary factor for these bulbs?

Yes i agree they are normally broad spectrum, but by no means perfectly balanced! Look at the graph below:

Arcadia Freshwater has a nice blue and orange spectrum.
Grolux has a more even balanced blue and red specturm but less intense in the blue.

Who would grow more: 4wpg arcadia or 2wpg grolux ...arcadia had the greatest intensity but growlux has the more balanced spectrum.

I think my biggest point also, is that when i first setup my tank, as a nooby i was looking to reach this magic 3wpg figure in whichever way posibble! Is it not important that we also stress the colour temperature as well as the wattage, thats what i am saying?

And from that question...surely there must be a relationship for optimum plant growth the encompases both these variables. If so, we may all be using high wattage lighting but really need a more balanced spectrum of light.

NOTE: when i say balanced, of course i mean balanced in terms of beneficial light for photosynthesis not balanced across the who light spectrum.

Chris

 

[RYO]

On reading through a few sites it seems in Europe we tend to use a lower colour temp than our friends across the pond.
Seems across there they hit around the 10000k regular. I think so long as you have the plants to out compete the algae and have sufficient lighting to meet the needs of your plants ,the balance of the tank is kept in check.
Most tubes now are broad spectrum tubes, tri or even quad band, but a lot of it is down to personal taste in the look of your tank.
I have special plant tubes that are under 4000k and give a horrid greeny yellow tinge to a tank on there own. So i supplement this with a higher (bluer ) 8000k tube to brighten the look.
All in all I'd say balance is the key rather than specific colour temp.

 

[Themuleous]

An interesting question Chris, however I think you're over thinking things here a bit. Yes I see your point about the need for decent plant tubes, but at the end of the day the more watts of light you have over a tank the more 'energy' the plants have for photosynthesis. As already said nearly all tubes are broad spectrum, in that they produce several wavelengths of light, as such unless you use a bulb that produces purely blue or red light (such as the marine bulbs) this point would seem somewhat irrelevant as every tube you place over a tank will produce light of a wavelength suitable for plant growth.

Yes there may be some discrepancy between the Kelvin rating of different bulbs but this (I would have thought) would be far less important than the difference between 1WPG and 2WPG. And trying to measure the difference in growth rate of plants under different types of bulbs woudl seems almost impossible, as there are probably to many other factors (CO2, ferts, substrate, every tank is different) to pin down the difference to just the tubes.

George has said he has grown plants under lights ranging from 3000k to 18000k.

Basically, yes there is probably some difference between grow rates of different Kelvin bulbs, is it more important than the WPG? I doubt it. A formula that incorporates both is likely to over complicate what should be a relative simple matter.

Have you read this thread?

Hope this hasn't just made the whole situation far more confusing!

Sam

 

[craynerd]

No i hadnt read that....excelent post and thanks for the link!

Does seem that i am over complecating things somewhat!

Chris

 

[Themuleous]

No i hadnt read that....excelent post and thanks for the link!

Does seem that i am over complecating things somewhat!

Chris

I think so too

 

[lljdma06]

No i hadnt read that....excelent post and thanks for the link!

Does seem that i am over complecating things somewhat!

Chris

I think so too

Pretty color light, bright light = pretty plants grow

Ucky color light, dim light = pretty plants no grow, get yucky algae, poopoo.

This simple enough? I'm being a stinker.

 

[Themuleous]

 

[George Farmer]

Providing there's enough light intensity to induce decent growth rates then colour temp. is almost irrelevant.

With lower lighting levels the spectrum becomes more important as the lower plant growth rates potentially allow more algae. For example I would not run 1 wpg with a high blue content tube i.e. 10000K. Running 3 wpg with plenty of CO2 and other nutrients with 10000K would be fine though.

Go for what tube suits your taste, budget and availibility. 6500K is generally best for bringing out greens, lower for reds, higher for blues. Although there are exceptions.