Led light color and amount

Discussions about fluorescent, LED and other types of grow lighting for Venus Flytraps and other plants
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Siiseli

 
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Led light color and amount

by Siiseli » Fri Jan 13, 2017 4:24 pm

Hello!

I have been looking into building new terrarium and I have been doing some research on lightning. I would want to go with LED lights and yestarday I stumbled on these at digikey:
http://www.digikey.com/products/en?FV=ffecd831
They look really tempting to me (easy to connect and pretty high effiency). I was thinking about buying fishtank about 120cm x 40cm x 40cm and I thought maybe two of those 1120mm long led "fixtures" would be enought (both roughly 4900 lm).
There is 5700K, 4000K and 3000K, I guess I should go with two 5700K or with one 5700 and one 4000K to get some red wavelengh as well? The spectrums can be found from the datasheet here:
http://www.bridgelux.com/sites/default/ ... %20A_0.pdf

I have done some research and I used the calculator (http://dev.edman007.com/~edman007/pub/par-dli-cal.html) mentioned in this thread:
how-much-light-do-you-really-need-t31035.html , to get some idea about how much DLI would I get with 5700K. The problem is that it seems it doesnt really calculate much of the blue vawelengths for the DLI, with 2x4900 lm I get DLI of roughly 10... Has anyone else used that calculator?

Thanks in advance for any help!

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nimbulan

 
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Re: Led light color and amount

by nimbulan » Fri Jan 13, 2017 5:02 pm

I've done quite a bit of reading about this lately, and all that I've read seems to indicate that lower color temperatures are better. Red is more photosynthetically efficient than blue, though blue acts as a growth regulator so you still need some of it. I was linked to a high end growlight company that does a lot of research into light spectrum and their indoor fixtures are rated at 3000k, while their supplemental lights for greenhouses are rated at 5000k (apparently you need more blue to offset the IR wavelengths from the sun.) I've been very happy with my 4000k LEDs and recently put together some 3500k (only because they were sold out of the 4000k!)

I used these Samsung modules: http://www.digikey.com/products/en/optoelectronics/led-lighting-cobs-engines-modules/111?FV=ffecd47f%2Cffecd480%2Cffecd481%2Cfffc05e6%2Cffe0006f&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=0&pbfree=0&rohs=0&quantity=0&ptm=0&fid=0&pageSize=25 They are more expensive, but the efficiency is extremely high so you save power in the long run and heatsink requirements are minimal. All you have to do is use thermal glue to attach them to aluminum C channels which double as reflectors.

ImageDIY LED strip lights by Nimbulan, on Flickr

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Siiseli

 
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Re: Led light color and amount

by Siiseli » Sat Jan 14, 2017 10:49 am

Thanks Nimbulan! Even thought they do cost more I did quick calculation that price + electricity cost will be about the same in one year with the ones I posted and they will save about 70€ for me in the promised 50000 hours lifetime!

How many of those led strips do you have one your terrarium? How many you would put in lets say 120 x 40 x 40 cm fishtank?

I guess the kelvin rating doesnt affect so much if the plants do get blue and red wavelengths. I have read posts about ppl using only 3000K and only 6500K and had great results with those... 4000K does look good because it has both blue and red.

Thanks again!

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nimbulan

 
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Re: Led light color and amount

by nimbulan » Sat Jan 14, 2017 4:36 pm

I don't have a terrarium. I generally aim for 2000 lumens per square foot of grow space for high light plants like sundews, which would be around 10,000 lumens for your terrarium. If you're growing Nepenthes, it depends on the species but you can likely use less.

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Siiseli

 
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Re: Led light color and amount

by Siiseli » Sat Jan 14, 2017 5:13 pm

Well I would want to be able to grow VFT and probably heliamphora too so I might need 3 strips to ensure enought light. Ofc they could do OK with 2 strips too, but it would be a shame if it would be too little.. You have been most helpful, thanks!


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