# 3W or 1W LEDs, which are better?



## Wasserpest (Jun 12, 2003)

This might be a bit obvious, but the advantage of 3W LEDs is that they are much brighter. For a "medium" tech tank I would choose (8?) 3W over (24?) 1W, and lift up the fixture a bit for better coverage. That's just an example of course, much depends on how much light you want and how hard you drive them.

But it really comes down to the decision of "fewer high wattage vs more low wattage" bulbs.

I am sure Hoppy can confirm with PAR numbers and such.


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## Hoppy (Dec 24, 2005)

You can use 3 watt LEDs, but only drive them to 1 or 1.5 watts. But, 1 watt LEDs are limited to 1 watt. That is an advantage of 3 watt ones, plus the fact that they are at a higher stage of development, so might be a better quality LED. My last LED fixture uses 3 watt LEDs, but I'm using them at 430 mAmps, so they are actually running at about 1.5-1.6 watts. I would get more light running them at 3 watts, but not twice as much, and they would run a lot hotter.

I think "the jury is still out" on how many LEDs to use for a given size tank. It depends a lot on what your goals are - do you want really uniform light, do you like seeing obvious spotlighting, are you using a mix of colors of LEDs, how high above the tank do you want the light to be, etc.?

For a small tank, like 10 gallons or smaller, I would use 1 watt LEDs, if they are a lot cheaper. For that you don't need the brightness of the higher powered ones. If they aren't a lot cheaper, I would still use the 3 watt ones.


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## DiscusLoverJeff (Jun 18, 2010)

Are there any good DIY instructions that break down how to make your own fixture as in where to purchse the lights, power supply etc?


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## Wasserpest (Jun 12, 2003)

Have you read the sticky in the DIY section yet?


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## DiscusLoverJeff (Jun 18, 2010)

My apologies, sorry for the post asking for DIY. I did read some nice projects in the threads and I have checked youtube as well. 

Question though regarding wattage. I know there has to be different "total" wattages for each size tank ei: 36", 48" 60" etc. tanks. And there has to be charts that tell how many bulbs and colors for say a reef, vs a planted tank correct?

Is there such thing as overkill on LED's?


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## trackhazard (Aug 24, 2006)

Definitely there is overkill as with any lights.

I think its helpful to think of LED intensity vs depth rather than overall volume. A 20H tank vs a 20L tank will have different needs when it comes to light even though their volumes are nominally the same. 

Most recommendations for LEDs are in regards to distance of lights from the surface of substrate and a target PAR reading i.e 18" off the surface gives you 30 μmol PAR for a given wattage LED running at X current. LEDs are still relatively new to the industry so a chart laying down what gives you what as you describe probably isn't around, especially with a plethora of DIY fixtures out there that all use different LEDs at different currents and different arrays. Your best bet is to do research on what other people are doing, make some estimations and then grab a PAR meter and take some readings to figure out how close you got. 

-Charlie


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## redfishsc (Aug 29, 2010)

snail said:


> I've read lots about DIY LED projects. Some use 1 watt LEDs others 3 watts. Thoughts on which one is better? I know the 3 watts get hotter. I'm thinking using more 1 watt LEDs will give better coverage with less heat problems but is there any reason 3 watt LEDs are still better?
> 
> This is for a 15 gallon medium (or low) light planted tank.


Hoppy covered this quite well, so I'll just add a few other tidbits to build upon what he said. 


There is nothing intrinsically special about a 3 watt LED. It's just (right now) the best bang for the buck, generally speaking. 

The LEDs that are generally called "3 watt" LEDs can be the most efficient LEDs on the market. The CREE XRE, XPE, and XPG are all very efficient LEDs. Yet if you buy a low-cost chinese LED (which I have done myself) you will NOT get the same efficiency. Not a huge deal, but it adds up. 

For example. 

Some chinese 3w LEDs struggle to make 100 lumens per watt. The Cree XPG cool white can hit nearly 140 lumens per watt. So literally, two XPG will put out about the same amount of light as three off-brand whites. And the XPG will use less energy. 


Now if you want to save money, look into Bridgelux LEDs. I received yesterday two Bridgelux 402 LEDs (www.newark.com, search for "bridgelux"). They are literally only $7 each, and bright as heck. Fairly efficient, and run up to around 7-9 watts. 

Three of these (meaning, $21 for LEDs) is plenty of light for a medium/high light 10 gallon tank if driven at 700-900mA. 

Or you could order 8-10 Cree XPG (which are actually more efficient, but also more costly) and spend $30-45 on LEDs. 


Both look nice and work well, and are dimmable if you have a dimmable driver.

One option is cheaper, easier, and slightly less efficient than the other. That's how LEDs tend to go. 

Right now the most efficient LEDs out there are the Cree XPG (3-5 watts at full power) and the Cree XML (up to about 9 watts). The Cree XML is the king right now (160 lumens/watt when driven at 350mA). For absolute maximum brightness (and slightly less efficiency) you have to drive them at 3.0 amps, and there aren't many drivers that have a low enough voltage range for use over a 5-30g tank without having light overkill. 

Thus bang for the buck (quality being considered as well) I think Bridgelux 402 and 802 are VERY good choices. Next in line is the Cree XPG--- will cost you more (up front) but they are more efficient than the Bridgelux. They ALL look great in cool white (roughly 6500K)



DiscusLoverJeff said:


> Are there any good DIY instructions that break down how to make your own fixture as in where to purchse the lights, power supply etc?


Also visit the lighting forum of www.nano-reef.com, they have a VERY hyperactive LED section and a monstrous DIY LED sticky. 


We have a pretty good LED thread in our DIY forum, and I plan on doing a write-up on my LED array for my upcoming 23" cube build, but time and money keep me moving slow, but steady. I have LEDs in the mail as we speak.




DiscusLoverJeff said:


> Question though regarding wattage. I know there has to be different "total" wattages for each size tank ei: 36", 48" 60" etc. tanks. And there has to be charts that tell how many bulbs and colors for say a reef, vs a planted tank correct?
> 
> Is there such thing as overkill on LED's?


If you see any such chart, take it with a grain of salt. 10 watts of cheap chinese off brand LEDs won't produce the same useable amount of light as 10 watts of high-efficiency Cree, Rebel, or Bridgelux LEDs. 


And yes, LEDs are actually VERY VERY easy to overkill. 24 Cree XPE LEDs, driven at full current (1.0 amps) put out a VERY similar light spread (and matching PAR numbers) to a 250w metal halide, if they are spaced evenly in a 10X20" space, using 60 degree optics. All the while, using roughly 100 watts. 

That would be gross overkill on something like a 25g tall, which I have used in the past (now empty... was a reef). Perfect for a reef, algae hell in freshwater.


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## DiscusLoverJeff (Jun 18, 2010)

Both of my 90/95 gallon tanks are 24" high with a 4" substrate, so 20" each. My 95 gallon is a wave tank with different measurements from corner to corner. My reef is 18" deep with only 1" in sand base. 

This is some good food for thought as to what I will need and how to do it. I love projects and this sounds like a productive one to say the least. 

Thank you for the information Charlie and Redfish!

PS: What about reflectors on this or can you find polished aluminum for a fixture or because of the LEd design, they don't require reflectors?


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## snail (Sep 22, 2010)

Hoppy said:


> You can use 3 watt LEDs, but only drive them to 1 or 1.5 watts. But, 1 watt LEDs are limited to 1 watt.


Thanks I didn't understand fully about driving the LEDS




Wasserpest said:


> This might be a bit obvious, but the advantage of 3W LEDs is that they are much brighter. For a "medium" tech tank I would choose (8?) 3W over (24?) 1W, and lift up the fixture a bit for better coverage. That's just an example of course, much depends on how much light you want and how hard you drive them.


Good point about coverage. This will be a low tech tank (no c02) But I tend to like slightly higher lighting than normal in low tech tanks, more towards medium than low, I like a bit of algae for my nerite snails 

Thanks redfishsc for the break down on brands, very helpful. I have been considering the cheap ones from e-bay, mainly because it is the easiest place to order from, I'm in Portugal. I don't mind spending more but being my first try I'm also thinking if it all goes wrong I won't loose much. It is a valid point about lumens per watt because one of my biggest interest in LEDs is because of what it will save me on the electricity bill, then I can have more tanks running


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## redfishsc (Aug 29, 2010)

www.cutter.com.au should ship to Portugal. They are based in Australia and seem to ship everywhere but the moon. 

You can get Cree there all day long, any kind, any tint bin, any color, any time. You will possibly be limited in your optics choices, and they don't always have the best driver selection/pricing, but they certainly have the best Cree selection anywhere.


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## Wasserpest (Jun 12, 2003)

snail said:


> Thanks I didn't understand fully about driving the LEDS


Think of it as dimming. For example, when you turn on a lamp, 220V (I assume) are driving the bulb and it lights up at maximum brightness. Same for your 3W LED, you can send say 1000mA through it and it will result in 3W being converted to light and heat. But, you can also just send 700mA or 350mA through it (if the drivers allow that) which will essentially turn it into a 2W or 1W LED - not as bright, not as hot, and perhaps enough for your plants.

One day you decide to add CO2, lots of fertilizer, and difficult plants. Then you can change the driver and push the LEDs to 3W. Point is, if you start with 1W LEDs, that will be the maximum wattage you can get out of them. With 3W, you have room to play.

Makes sense?


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## snail (Sep 22, 2010)

Okay, thanks for all the info I'm clearing up some of my questions.


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