Can output of LED's be converted in an understandable way?

[Jomega]

Hi there

I hope Im not asking a silly question here, but I have just recently moved over from marine's and i have a wee problem. I will be using an LED fixture over my tank.
Total it produces 160w of power. Given that one of its channels is alot of blues, and the fact that I want to run a low tech tank without co2, but still heavily planted, I will be using only the white channel. This white channel, which is mixed LED's of 8000k whites, 3000k reds, and some 450nm royal blues, should be adequate to get decent plant growth, and will produce around 65w of power. I can manipulate the power output (ie I can run it on any percentage i like - like 50%) .
The question i have is - as I understand it, LED's pure wattage cannot be used as an indication of how much par they will put out. So 65w of LED's will often produce more par than 60w of T5HO's.
Is there any mechanism by which any one knows or can estimate how much storonger LED's are comparitively, so that i can get an idea of how high / low I set the white channel on my LED's. I know it's probably down to the LED's themselves, but i am just taking a gamble someone very clever has worked this all out 🙂
Any feedback would be most appreciated.
regards
Jo

 

[BigTom]

As you mentioned, PAR is what matters. If you have a PAR meter then you can measure it, anything else will just be complete guesswork. What size is the tank?

For reference and the vaguest of comparisons, I have a 36w Kessil a150 2 feet above the substrate on my 3'x3' tank and that seems to be plenty for low tech.

 

[Nathaniel Whiteside]

My maxspect razor 160w apparently outperforms a 400w halide. With a very similar setup to what you describe.
I'd say a rough pound for pound measurement is 3x t5.

..but, par is what matters, and is highly variable, setup to setup.

From Maxspect Website:

 

[Jomega]

Hi there guys

thanks for the responses.
My tank is a three foot by two foot. and its shallow - around 18 inches high.
I have a 160w razor too Nathaniel... Is yours the 8k specifically for plants? Mine is the 16k version, thus me only using the white channel.
If it appears a 36w kessil does the trick in a three by three, i might just be alright running my white channel at 50% for six hours a day...
Probably going to be alot of trial and error, as the plants mature.

 

[BigTom]

Sounds about right. You could probably go a longer photoperiod if needed (mine gets about 12 hours).

 

[Nathaniel Whiteside]

Hey Jomega,

Yep, mines 8k for plants, but they'll grow in Anything. Just Aesthetically the 8k gives me a wide range of colour spectrums from orange to light blue.

Cheers,
N

 

[Jomega]

thanks for the reply NAthaniel and Tom 🙂
cheers