Led Theorys And Calculations

[Craig89]

Ok so a lot of people (me included) are turning to LEDs for lighting aquariums but are they good enough for a hi tech planted tank.

I've done a little research today, and will continue to do more but here's what I've found so far:

The watts per gallon rule will not work when trying to calculate how many LEDs you will need, watts per gallon is very basic and very outdated. Watt is not a measure of light output but a measure of power so generally not good for calculating how much light is needed. I know alot of people use it and it seems to work for fluorescent tubes but not for LEDs

I've also found that the "colour temperature" also plays it big part in plant growth. Reading a number of studies it seems That a colour temperature of between 6000k - 6700k is best for freshwater plant growing.

It seems a good way (so far) of calculating the amount of LEDs is to compare the lumen output, lumen is the amount of visible light that can be seen by the human eye.

Now a standard 32w T8 tube produces 2600 lumen which calculates at 82 lumen per watt.

I've found some 1w LEDs are producing 125 lumem so that equals 125 lumen per watt.

This is more than a 50% increase in useful visable light.

This is as far as I've got so far as I'm at work and should really be selling houses lol. I'm going to continue my research tonight but if anybody had any more info or ideas please feel free to input your findings.

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[SO19Firearms]

WPG came from (I believe) T12 lighting, meant less for T8 and now largely ignored for T5.
Colour temperature - studies aside* - is largely worth ignoring, between 6500 and 10,000 will see you right.
PAR is probably where you should be directing your reading, it gives the answers you're looking for - I think PS3Steveo was in your boat while researching making his LED setup, it might be worth checking his posts.

IMO




*Studies are good and they may even spit out the right answer when it comes to growing these weeds, but if some guy is using a 10,000 bulb or non- "plant" bulb with marginally less growth but a tank he's happy with the colour off - I'd go with his anecdotal evidence over a lot of studies. IMO

 

[Craig89]

Yeah studying PAR is tonight's job, I also stumbled across a calculation that suggested today's LEDs (6500k) would work out as needing 0.6 WPG if compared too a t8 bulb But lots more to study

 

[DrRob]

*Studies are good and they may even spit out the right answer when it comes to growing these weeds, but if some guy is using a 10,000 bulb or non- "plant" bulb with marginally less growth but a tank he's happy with the colour off - I'd go with his anecdotal evidence over a lot of studies. IMO

That'd be me then. I love my 10k bulbs, much cleaner fresher light, and the plants still grow like weeds with the CO2 and ferts.

 

[ian]

I use LED's in my high tech planted tanks and they grow plants well. I use TMC grow beams, with good effect. As for K ratings...take them with a pinch of salt, this was a rating that aquatic companies held onto to help sell their bulbs, when in essence you could buy the same bulb for just a few quid.

have a read here (the decent discussion regarding the matter starts half way down the page)

http/www.fishforums.net/index.php?/topic/395587-lighting-for-basic-ow-tech-plants/

You will find that a fair few aquascapers including George farmer are using LED's with good effect. I love them, they give a distinct look to a tank, also plant giants ADA have just brought out some LED lights...that tells me they are the future.

TMC rate 1 grow beam equivalent to 1 x 24w T5.

 

[Craig89]

Thanks Ian will give that a read tonight

 

[Craig89]

Makes for some very interesting reading seems opinions are divided. Might just be a case off seeing what works best and running with that.