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How does L.E.D compare to fluorecent ?

2232 Views 4 Replies 3 Participants Last post by  redfishsc
I recently got another tank and i was wondering how much led watts i would need for a 48x18x20 and a 48x18x18 the first one will only be 70% filled with water and the second one will be full. just to let you know i would like medium or medium low light levels ???
I was wondering about gu10 leds as they produce the same amount of light as 50watt halogen bulbs but they use 3 watts
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There is no good answer for this question, especially when you are planning on using LED fixtures like the one you linked. Using those kinds of lights is just fine, by the way, and a good idea in general.

Here's why:

LEDs will vary significantly in their efficiency. They do tend to be more efficient than most fluorescent lights, but ones with small emitters (under 1 watt each) just don't have the punch we need to put light on the sandbed.

I own a white 7 watt PAR30 bulb that has 25 or 50 (or more..??) LEDs. At 7 watts it barely farts out enough light to be used as a night light in my toddler's bedroom. Actually works quite nice for that.

Yet if I were to put in there 7 watts of high power LED (say, a couple of Cree XPG) then I could easily read a newspaper from 10 feet away. Very bright.

The lamp you linked only uses 4 watts or so but has 20 LEDs on it.

Trust me, it won't work for any but the most low-light plants, and even then, I wouldn't bet on it.

Look for bulbs that have, preferably, 1w or 3w LEDs.

From there, assume that you'll need to get roughly 2 "watts per gallon" for a medium light situation. But I say that with no guarantees since these lights can vary a LOT in their build quality, LED brand/color temp, and drive currents.

If you don't mind spending the money, go to and browse their "Evil" Par38 lamps. They are made for reefs but I think you can get them with all white, or you can go with the 12K look (which you may not like, it's quite blue).

If you got the Evil PAR 38 bulbs, get ones with 80 degree optics, or get 60 degree optics and hang the lights VERY high for a good light spread. Either way you'll be playing around with hanging-height to get the light spread right.

You'd want at least 2, probably 3, to avoid spotlighting. Not cheap, but these are very well made lights.
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thank for the reply, i just got a 860 litre tank today and they threw in a arcadia t5 2x 39w light and 2 arcadia 40w t8''s so i wont bother with L.E.D's
18" = 0.4572 m
48" = 1.2192 m
0.4572 m * 1.2192 m = 0.55741824 m2
320lumens / 0.55741824m2 = 574.0752 lux

If you use six of those you would get 3444lux at the surface(assuming that all the light is hitting the surface). I think that 3000lux(at the bottom) is the absolut minimum you should have in a planted tank. 12(=42w) of them would be medium light level ???
^^That is, if (a huge IF) the 320 lumens is a correct number.

I'd wager that it's inflated.

Beyond that, the light intensity would not be as much as you'd think even with multiplied numbers.

Just as a good illustration, check out these two flashlight videos. The first one has 500 small LEDs and runs at 50 watts. Neat as heck and an AWESOME DIY achievement.

The second uses only 1 LED, a Cree MCE running somewhere around 12-15 watts. Yet look at how much light it throws off. His pics aren't as dramatic as the first video but he's producing about the same amount of light at 1/4 (or less) of watt usage.

Small LEDs are definitely NOT the way we want to be looking.
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