# How does lighting requirement work when using LEDs



## flyingmomo (Jul 6, 2017)

Usually I have read is Lighting requirement or level is counted by watts per gallon(wpg?) . So say 2wpg is low tech while 6wpg is Hi tech. But LEDs are quite effecient and lower powered for same output comp to Cfl bulbs. So say if I plan to use LED bulbs for a low tech tank, what should I consider?


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## Boreas (Dec 8, 2015)

What are you trying to grow?

I have a low tech tank and I use a 48w beamswork led light. My lights about 22 inches from my substrate.

Most people would say watts per gallon is outdated. PAR is the standard, which is the intensity of light output. The further your light is from your plants, the weaker it gets. ie: How deep your aquarium is, or how high above the surface of your water you light is affects your PAR. A more powerful light outputs more PAR.


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## flyingmomo (Jul 6, 2017)

Boreas said:


> What are you trying to grow?
> 
> I have a low tech tank and I use a 48w beamswork led light. My lights about 22 inches from my substrate.
> 
> Most people would say watts per gallon is outdated. PAR is the standard, which is the intensity of light output. The further your light is from your plants, the weaker it gets. ie: How deep your aquarium is, or how high above the surface of your water you light is affects your PAR. A more powerful light outputs more PAR.


Mostly low tech plants. I already have a 32W T8 tube for my 20gal long. Was thinking of adding few clip on lamps with LED bulbs. Any site I can calculate PAR?


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## coldmantis (Apr 5, 2010)

flyingmomo said:


> Mostly low tech plants. I already have a 32W T8 tube for my 20gal long. Was thinking of adding few clip on lamps with LED bulbs. Any site I can calculate PAR?


20g long and 32w T8? that doesn't make sense unless your using a 48" fixture on a 30" tank? T8 bulbs for 30"(24") tanks are usually like I think 18w max.


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## infolific (Apr 10, 2016)

flyingmomo said:


> Mostly low tech plants. I already have a 32W T8 tube for my 20gal long. Was thinking of adding few clip on lamps with LED bulbs. Any site I can calculate PAR?


You can't "calculate" PAR. There is no way to go from lumens, watts, or lux to PAR. It is provided by the manufacturer or measured by hobbyists with a PAR meter. Some places rent PAR meters. The numbers provided by manufacturers are often inaccurate for real-world situations so I would rely on reviews from trusted sources instead.

The really high-end lights like those from Kessil seem to have more PAR than most people need as I see people post that they're running their lights at 30% or 50% or something much less than 100%. Such lights seem like overkill for a 20 gallon though.


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## flyingmomo (Jul 6, 2017)

infolific said:


> You can't "calculate" PAR. There is no way to go from lumens, watts, or lux to PAR. It is provided by the manufacturer or measured by hobbyists with a PAR meter. Some places rent PAR meters. The numbers provided by manufacturers are often inaccurate for real-world situations so I would rely on reviews from trusted sources instead.
> 
> The really high-end lights like those from Kessil seem to have more PAR than most people need as I see people post that they're running their lights at 30% or 50% or something much less than 100%. Such lights seem like overkill for a 20 gallon though.


Its a 36inch T8 light fixture for aquariums. Someone suggested I use LED floodlights to add more light. Sounds like a good idea. I want decent DIY light because the professional aquarium lights are very expensive


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## coldmantis (Apr 5, 2010)

Go for it, DIY is always fun, I used one of those flood lights before on a 7.5 cube, 12x12x12. I think it was either 10 or 15w. I thought the coverage and colour was garbage but I'm used to t5ho and I always dislike Leds. But since you have such a short tank it could work you will just have to buy like 2 or three of them. I heard they overheat and short out fast so make sure you diy some sort of fan cooling for them. Out of the 8 freshwater tanks I have running only 1 is using leds and it does a good job but the tank is small only a 5.5g.









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