What is the equivalent in LED to 400w MH?

Comparing one lighting method to another just won't work, it's like apples to oranges. Heck, even comparing one 400w halide fixture to another doesn't work very well, as there are all sorts of reflectors, housings, ballasts, bulbs, etc.

Here is a good write up illustrating why comparing LED lights to metal halides isn't practical.

 

The CA blog is good, but let's break the question down into it's components and keep it even simpler.


- First, energy and light are the same thing. If you have X amount of energy, you really have X amount of light.

- Light can be defined as wavelengths of loosely speaking "colors".

- Some light sources will produce different "colors".

- Sources such as metal halides produce a wide range of colors, while sources such as leds can produce much narrower ranges of colors.

- Corals need certain colors to obtain energy. This area is not that well understood. Some corals need specific colors, others just need light that falls in some given range of colors.

- If we define a range of colors that corals can possibly use, then we can define the efficiency of a light by how well it distributes energy into colors in this range.

- If we pick a lightsource that has just has 1 color in this range, and another that has a wide range of these colors, but also has some energy distributed to colors outside this range, that don't count, then the light source with just 1 color will be defined as more efficient.

- So, as leds can be tweaked to produce very specific colors, they can be labeled more efficient. However, all things being equal, there is only a slight difference and that is due to the relatively small amount of extra spectrums (i.e. wasted energy) generated by the MH.

- However, if you have a coral that needs one color specifically, say green and your light source is a blue led, you could be providing no light for that specific coral. On the other hand, the MH, although, "less efficient", may provide a wider range of light and give the coral the correct color. This is more true though for wider spectrum MHs, such as 10000K lights though, than say 20000K lights, although, in reality these labels are created by a marketing department and don't really represent the color spectrum as they theoretically should, so, it's a bit inaccurate, in practice to say this.

- Also, the above is if all things are equal. All things are not equal, we are not just trying to produce light of a given range of colors, we are trying to focus that light at an fish tank with a specific size and shape.

- Leds have another potential advantage, being that they can focus light much better.

- For a MH, you can produce a very good reflector, but that reflector will generally reflect light, in roughly an even, circular pattern.

- leds will reflect light in a circular pattern, but each led, produces a small circle of light. These can be spread out, to light to fit a very specific shape better. As our tanks are elongated rectangles, leds can fit the shape better. For cube shaped tanks, for example, this difference in light-focusing efficiency is therefore essentially non-existent if a good reflector is used for the MH. Of course not all reflectors reflect light well.

-Also, to go deeper, light needs to be more focused. With an led, although you can focus light better, it is distributed into smaller packets (each led). So, the more you focus the light, the more leds you need to add. With a MH, the more powerful bulb you need. With leds, you can remove some excess though, if they are not helping to cover the correct area. There is less you can do with a MH reflector to tweak the coverage area.

- So as others have said, a comparison is difficult, as we need to consider the specific spectrum of light, without really knowing what spectrum are best for our corals.

- It is likely that an led may be better for one group of corals and MHs better for another... And one metal halide may be better than another MH for one group and worse for another etc... However, there isn't much info with regards to specific corals.

-Generally speaking though, if you are providing light in a specific range of colors, defined as "PAR" you are likely providing your corals with a reasonable amount of useful light, although truly defining efficient with regards to distributing energy to the "correct" colors is virtually impossible with the information available.

- Reflectors, ballasts and other equipment also make a difference as they are also involved in distributing energy to different colors and focusing it to a given area.

-So, in answer to your question, there is no answer.

 

^Yes x18.

 

Excellent bit of knowledge there, thanks for bringing this up Mike, I wasn't aware but now I am. Thanks

 

As for M2434's response, to sum it up to all us ignoramus's out here, (i.e. myself) It really all depends on what you plan or already have in your set-up and what type of environment you plan on creating.....but I still like the way you said it. lol

 

150W LED light can be equal to 400w MH.

My friend bought 150w lights and have a better effect than MH light.

 

90w LED Aquarium light can replace standard 300-400W MH/HPS aquarium light , 120W LED Aquarium light can replace standard 400-500w MH/HPS aquarium light .

 

I have seen many LED units that can provide or even exceed the max PAR output of a 400 watt MH. What I have yet to see is an LED of that size provide that output and also provide the spread of a MH.

 

Got this email from ecoxotic.com

 

LMAO, leave it to a sales dept to make ridiculous over-generalized statements. Remember, their job is to sell products though.

Pay attention to what I said about focusing light and what gcarroll just added. The exotic cannon may have the same PAR as a 400MH, but only in it's bright spot and will not have the spread.

However, the spread of a 400MH may be too wide for a rectangular tank, so you may not need the spread.

Really though, all things being equal, a led of a given wattage is approximately equal to a MH of a given wattage.

Usually things aren't equal though....

You can gain a slight advantage by directing the light energy to more specific color spectrum. In practice this is probably less than 10% difference though (I'm going from memory, so that number may be off a bit, but it isn't a huge number).

The bulk of the efficiency gained by an led is because of the flexibility available to spread the light out to very specific shapes, such as a rectangle.

So, if you have a 1/2 cube tank, i.e. a rectangle, then the led could potentially be up to 50% more efficient +/- some spectral efficiency.

So, for the entire 1/2 cube i.e. rectangular tank an led will never be much more than 50% more efficient. I think really not even that much in practice. Although, you can focus light more with the led and make a small part of the tank more than 50% brighter with the same Wattage, but not the entire tank. Maybe you only want an small area to be brightly illuminated, then you could run lower wattage.

If you consider the light over the entire tank, the led will typically not be more than 50% more efficient. So, a 200W led would be roughly equivalent to a 400W MH, but there are a lot of factors, such as reflectors, height tank shape etc... really, the difference will likely still be less than 50%.

For a cube, the difference would likely be less than 10%.

The Canon does look very good though, I don't mean to say otherwise, just their reply is ridiculous.