That 12W = 175W article has come up before. Do a search on it. I put quite a few details down on that thread but will re-hash a brief flavour of it in a sec.
I've long said that many of the retail LED units miss the advantages of LEDs.
Using a pizza as an example Do you spread all the little bits of topping out all over the bread? or is it better to put them into 2 lines? or into 2 squares?
BY this I mean to make full use of LEDs advantages they should be well spaced out and not pushed into tiles or into tubes.
However that would not suit the aesthetics side. People do not want lights that are the same footprint as their tank. Even if they would get a better result for less power
Now on the flavour of the LED vs MH vs Fluoro.
Like all subjects to make a comparison you have to be looking at an equal or as close to before you make the comparison.
There's no point comparing 12W of LED that is focused downward to 175MH that is unfocused with only a reflector. Thats like putting 1 plant in the garden under a magnifying glass and the other not.
PAR data would suggest that you need a third of LED light to match MH for PAR and a quarter to match for PUR.
I would suggest that Fluorescent is a little better than MH watt for watt because you can use several point sources rather than a single one. A little like one advantage of LEDs, This is why I always suggest that T8 is a better choice of fluorescent than T5HO.......because you can use more tubes using the same wattage and be able to spread them out.
I would suggest LED is 2x Fluoro.
Then you will get the naysayers that say Only X version LED or better is suitable and the cheap far east knock offs are useless. That is pure snobbery really. Much like someone being proud of their ADA gear many DIY LED owners are proud of their 'hi spec' renowned brand name LEDs
Well my unit was built in January 2009. Cheapo ebay China Luxeon 3 copies. Still going strong. Still growing plants. Never had a replacement. They can't be that bad but some will say you need Cree or bridgelux etc. lol
Do I have proof my spread out DIY is better than a retail aesthetics first unit? No I have never tried them or tested them. However I would doubt that the T8 replacements are a great use of the technology (see pizza similie above.) The tiles are probably better as they make use of spread a little bit better.
But in my (untested) opinion the whole footprint and good spacing will win the day over the slimline aesthetic whether it be fluoro or LED and both will beat MH because of this reason. This of course is PAR per watt of usage.
As a guide I have my 1.12WPG of LED 28" above the substrate and only use 1.12WPG of it for the central 5 hours of a 9 hour photoperiod.
As for TGM's reasons maybe they are experiencing what I suggest above. However for them to make the comparison and find the LEDs not to match the fluoro standards they would need to be using spaced out fluorescents or much more power. I'm not defending them at all. I believe LED is far superior to other forms of lighting.
So in summary. Are LEDs better per W for growing plants - There is argument. They definately are.
Are the claims made by the retailers of how much better they are true? I doubt it. Yes the actual LEDs figures may give these percentages/statements but the fixtures they are then put into negate a certain amount of the LEDs advantages.
Is any LED unit going to be worse than fluoro/MH? It would have to be a very poor unit not to be better PAR for Watt. The question would have to then be how much % better does it need to be to justify the investment. If it works really well then spending 3x to use 3x less and last twice as long is a pretty sound investment. If it is 1.2x then of course it becomes more of a moral question and not an economic one.
As for LED colouration you can get whatever colour you want from one LED!!! The lights in the picture link below(click on it to see some more colours )are ambient lighting strips using 30 RGB LEDs per meter. The give a nice glow behind the TV. I can choose any of 30 colours and the blend the RGB colours to produce the chosen colour. Its not that it can only do 30 shades. However it would be a massive remote to put every incremental change of colour on it. lol.
This variant wouldn't be suitable for aquarium use though. There are RGB LEDs out there that are suitable though. I am just showing that LED is not limited to any fixed colouration. And these are pretty cheap to boot
Andy
