my new acyrilic led build

[Floyd R Turbo]

That is the exact same fixture. Click the "tech specs" link and the words are copy/paste exact.

There are several telling items that mean this fixture it not powerful enough for a scrubber. #1 is that the thing only weighs 0.67 kg. That means no heat sink. They are listed as 'no' = normal output, not high output. high power means nothing and it just marketing. 0.5w LEDs are just the small ones with leads that stand off the board. high power LEDs need to be mounted to a PCB board and a heat sink.

You need one like this one

http://www.ebay.co.uk/itm/120W-LED-Grow ... 2c5e45aa78

to do it right. Not that exact fixture, because it has the wrong spectrum LEDs in it, but you get the idea.

whoever told you that fixture would replace a 250W HPS scammed you. Really. There's just no way.

[Mrcgibb]

one new led unit arrived today , wow its bright ! so for an experement i have put it over half my mud filter and other half lit with 20 w compact flouresent i am shocked at how bright this is

pics of sump

[rygh]

Lights look pretty good to me.
No surprise that it is a whole lot brighter than a 20W CFL.
And that is seen with human eyes, which means that for the chlorophyll bands,
it is WAY brighter.

Probably not the most efficient with those little 0.5W LEDs.
But still way better than CFL.

A bit low on the blue end. Maybe. Nobody really knows for sure.

They will probably get a bit toasty with no heat sink. And thus not last as long.
But at only 0.5W, not a ton of heat from each one.
So just make sure there is some air flow on the LED side of the fixture.

My only real concern is the energy density (As was voiced above by others).
At only 45W, (which it does seem to be at 112 * 0.5W), for a 12x12 fixture, that
is a bit low on the watts/square inch. But not too bad.
Make sure it is really close to your screen.

[Floyd R Turbo]

The problem is that these are likely these type of LEDs (5mm, normal output, "super bright")

http://www.ledssuperbright.com/5mm-led-c-6

And this recently posted by SM

viewtopic.php?f=9&t=1504

Means that the intensity of these will drop off faster than CFLs will.

[rygh]

I doubt they are the little 5mm. Those are lucky to be 1/10 watt.
I would think they would be the newer 10mm ones. Some of those go to 1/2 watt.
But hard to say, since that ebay add is a little short on real technical data.
And if they are those 5mm, you are totally correct.

Hey Mrcgibb, maybe you can measure them, and give a closeup?

As far as that table - I call BS. (Not on SM, but whoever wrote it)
Sorry, but they have the 80% point at what looks like 2,000 hours. That is a total joke.
While I may not always believe the 100,000 hours they claim now, 2% of that seems rather low. :?
Some grad student is either clueless or has an agenda to sell Cree.

[Ace25]

The study was done in 2003, LEDs have come a long way since then. Also those are 1/4w 5mm LEDs they are referring to. Having used those (in blue) for moonlights I will completely agree with that scale. They do drop off in intensity rather quickly. The "high power" LED listed on the chart could have been referring to 1/2w or 1w LEDs back in 2003, which if that were the case the light panel above would actually last a long time.

[Mrcgibb]

The LEDs are the 10 mm type the other 14 watt panel uses the small LEDs ie 225 5 mm LEDs the light has been on all night and little heat LEDs are still warm to the touch I will task some more pics today of the reach of the light and spread

[Floyd R Turbo]

ace is probably right, they're probably 1/2W. See how it goes I guess. I just know that if you're not putting in enough power to generate some kind of heat that must be sinked away, then you're not putting out enough light. That, and the fact that you're putting these on a large screen for a large system, it will grow some algae, but it will be barely scratching minimum filtration. IMO.

[Mrcgibb]

My screen is 12 x 12 the light unit is 13 x 13 inches

[rygh]

Good to hear they are the newer 10mm ones.
And if it is only warm to the touch, seems like heat is not an issue.
Or I guess, could be lower power than advertised. That would fix heat as well unfortunately.

Assuming roughly 50% efficiency, and that another 10% is radiated away as infrared,
that leaves only about 230 mW of heat to really dissipate through convection.
A pretty small number, even on a tiny LED.
Some of that will even go back through leads, to PCB.

Well, time will tell if it works or not. I hope it does.