# How to determine LED Wattage



## shellydsilva (Aug 3, 2010)

Hi All,

How do we determine the LED wattage required for a planted tank?

I had generally read that 2.5 to 3 wattage/gallon is the thumb rule for the lighting of the planted tank.

When it comes to LED, how do we calculate the wattage required?

For an Ex, for my 35 Gallon tank, how much LED wattage do I need to put?

Regards'

Shelly D'silva


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## Supercoley1 (May 28, 2007)

Nothing scientific but I use an average of 0.6WPG of LED to achieve higher growth than I used to get with 1.4WPG of T5HO.

I would suggest (although have no proof) it isn't just down to it being LED. Some of the improvement is down to the ability to space the light much better. By that I mean rather than have the light 'forced' to be supplied in a 'fixed' area (the length of a tbe for example you can space it out more gridlike and that means you can then get a more equal even spread over the whole footprint.

I dare say if I lined up the LEDs in 2 lines as the T5HO were then growth might be closer W for W but that's the whole point with the LEDs. Less power consumption, more efficient for the same growth.

So to use my 33USG as an example I have a potential maximum of 36.75W (1.1WPG) of LED. This is used only for the central hour of a 9 hour photoperiod. This is all 5 series of LEDs on. Either side of this I stagger the lighting from 1 series up to 5 and then back to 1 so the light 'simulates' sunrse from the left and sunset to the right. Therefore the first and last hour is only 7.35W (0.2WPG)

In summary if you get the spread right you can aim for about half of what you would consider an 'ideal' wattage of T5HO, however I would suggest that on a tank of your size you can grow whatever you want at a pretty fast pace with 1.5 - 2WPG of T5HO. 2.5-3 is a little OTT IMO although masses of others disagree. 

AC


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