48" LED Array - Up and Running...Mostly

[Canadian]

Originally Posted by StirCrazy

Andrew, you have to go do some reading in this thread, he is getting higher par at 5 times the distance. T5 was at 3.5" and he is still getting higher PAR at 17" above the tank, which he did becasue he didn't have his dimming setup done yet. At 8" he was over 500 PAR where at 3.5 with the T5 he was at 300 PAR, Also this is with 60 and 80 degree optics, no one ever said thoes optics will give you 250 - 400 MH levels, it is 40 degree optics you need to get that, the best you will get with 60's is around a 150 watt MH which he is pretty close to as a 150watt mh isn't much higher than a good T5 set up. if you want a good comparason maybe Ron will take a PAR reading at 3.5" with the LEDs then you can see how much more punch he is realy getting, I am going to guess that he will be around 700 at the surface and probably close to or over 400 at the bottom, but thats a guess.

now as for the PAR output, you are thinking along the lines of a gas filled cathode tube. you can't think that way with LED as there is no gas to break down and change the spectrum. it has been showen there is absolutly no shift in spectrum in a LED over its life, only a 15% decrease in intensity, so there is no reason to think other than a 15% decrees in PAR as there will be no spectrum shift to compound the drop as it does in MH, PC, CF, ect. so if we look at that the average MH has a 20% drop by the time it is changed, and most of that drop occures int he first 6 months, floressents have a even steaper drop off, so going with LEDs after 5000 days (10 hours per day) you will have 15% less intensity with no spectral shift so you should not get nusence algae ect..

Steve

Steve,

You'll have to read Ron's post after yours. The PAR measured with the low quality T5 fixture was on more than 1 year old T5 lamps and therefore a very poor comparator - forget about the height of the fixture comparison. Additionally, I'm less concerned about the comparison to T5s than I am to MH (the only reason I commented on T5s was because the comparison was hugely favorable to the LEDs based on the manner in which it was performed). Various qualities of LEDs make them favorable to T5s IMO. With that said, comparisons are being made all over the place to MH by retailers, manufacturers, and hobbyists. When you were standing on your soap box about MH a few months ago you pounded your chest about getting over 1000 PAR at the surface and 500 on the bottom of the tank. Clearly, the numbers being reported here don't fall in line with what you've purported constitutes adequate PAR for your SPS tanks.

And as far as the theory behind intensity drop in LEDs goes - it's just that: a nice theoretical expectation based on presumed qualities. Until there is some long term data for PAR the theoretical musings can carry on but with a healthy dose of skepticism.

[Ron99]

Originally Posted by Canadian

Steve,

You'll have to read Ron's post after yours. The PAR measured with the low quality T5 fixture was on more than 1 year old T5 lamps and therefore a very poor comparator - forget about the height of the fixture comparison. Additionally, I'm less concerned about the comparison to T5s than I am to MH (the only reason I commented on T5s was because the comparison was hugely favorable to the LEDs based on the manner in which it was performed). Various qualities of LEDs make them favorable to T5s IMO. With that said, comparisons are being made all over the place to MH by retailers, manufacturers, and hobbyists. When you were standing on your soap box about MH a few months ago you pounded your chest about getting over 1000 PAR at the surface and 500 on the bottom of the tank. That's all I am trying to say. I would love to compile Clearly, the numbers being reported here don't fall in line with what you've purported constitutes adequate PAR for your SPS tanks.

And as far as the theory behind intensity drop in LEDs goes - it's just that: a nice theoretical expectation based on presumed qualities. Until there is some long term data for PAR the theoretical musings can carry on but with a healthy dose of skepticism.

First I think you are being overly critical of my light fixture. I would not call it low quality but about a middle of the road one. Sunlight Supply makes good fixtures and these were not much different then the first generation Tek fixtures in terms of lighting output. Slightly better reflectors and active cooling would improve it somewhat but how much do you think that would be? 10%? 20%? Secondly, while the bulbs were old, the only references I could fine say that T5s lose about 10% output over 2 years. The problem for reef tanks is the shift in colour which can lead to undesirable algae etc. But let's say that the degradation was 20% for the sake of argument. So my 300 PAR with the T5s could mean 375 PAR with new bulbs. Still much less than 500 PAR with the LEDs higher above the tank then the T5s were. Argue all you want but however you set up my test, new bulbs or not etc. my LEDs handily outperform my T5s. That's all I am claiming. I would love to test different lighting setups for comparison but I don't have easy access at the moment. Maybe we can do that and arrange to test various people's lights with the same meter which will give some idea. it's not as good as a side by side comparison under the same conditions in the same tank but it would be a start.

I would also take manufacturers claims with a grain of salt as they are in the business of marketing their products and most likely set up tests to skew results in favour of their products. However, independent test are being done like Sanjay Joshi's comparison I linked in my last post. That clearly showed the "lower quality" LED fixtures performing as well at or slightly better then a high end T5 fixture and only 15 to 16% lower output then a good 250W MH setup. Dr. Joshi is an engineer and has been testing all sorts of lights, especially MH, for a long time so I would consider him a good independent reviewer. Here's also a more recent review of a top of the line LED fixture, the AquaIllumination:

http://www.advancedaquarist.com/2007...searchterm=PAR

This one clearly shoes the AI unit outperforming a 250W MH unit. Granted, the MH ballast used may not be top of the line but is probably typical of one used by many people.

With respect to who has the biggest PAR; really, who cares. Stoney corals appear to photosaturate between 400 and 500 PAR so having 700 or 1000 PAR is probably pointless other than for bragging rights. I doubt it will do the corals much good.

As for longevity and degradation of LEDS, that is fairly well established. While high powered LEDs are fairly new to our hobby they have been around for a decade and are well tested. Low power LEDs have been around far longer then that so the degradation of LEDs is well understood.

[Dyspnea]

You have done a great job, look amazing! Still debating myself whether i should buy myself at 4 foot MH fixture or be adventorous and build an LED setup myself.

[Ron99]

Originally Posted by Dyspnea

You have done a great job, look amazing! Still debating myself whether i should buy myself at 4 foot MH fixture or be adventorous and build an LED setup myself.

Thanks. I say go LEDs. You won't regret it. Lots of people are having great success with DIY LED setups.

And just to throw more fuel on the fire I should add that that last review I linked to was a test of the first generation AI fixture. The second generation should perform even better as it uses the latest Cree XP-G LEDs that have higher output than the SSC ones used in the first gen fixtures.

[Ron99]

Played around lowering the fixture and found that the colour blending and overlap of the emitters wasn't great in the upper portions of the tank with the lights 3 inches above the water. PAR was between 550 and 600 in the upper part but stayed at 500 in the middle of the tank and was close to 400 at the bottom. I think that to get optimal blending of the light from the emitters and good overlap 6 to 7 inches above the tank is about as low as I will want to run them.

[Dyspnea]

What are you planning for livestock? SPS, LPS, clams, zoa, softs... etc?

[Ron99]

Originally Posted by Dyspnea

What are you planning for livestock? SPS, LPS, clams, zoa, softs... etc?

All of the above I currently have a mixed bag in the tank with SPS, LPS, softies, and zoas. I hope to be able to keep all of them with careful positioning. But I already found the T5s were to much for some of the LPS and had to tuck them under overhangs etc. I would like to add a small clam if space permits but we'll see.

Also, this latest news as of today is interesting. LEDs are only going to get better while MH and T5s etc. are pretty much as good as they are going to get now:

Cree, Inc. (Nasdaq: CREE), a market leader in LED lighting, announces a breakthrough new lighting-class LED platform, the XLamp® XM LED. This new single chip LED delivers record-breaking efficacy of 160 lumens per watt at 350 mA. The LED also delivers 750 lumens at 2 A, which is equivalent to the light output of a 60 W incandescent light bulb at less than 7 watts.

“This new platform continues Cree’s well-established record of turning R&D innovations into products,” said Chuck Swoboda, Cree chairman and CEO. “We continue to set the pace for LED performance, establishing new benchmarks that make you wonder why anyone would consider last-century’s energy-wasting technology.”

A cool white XM LED driven at 350 mA can produce 160 lumens at 160 lumens per watt. The new platform has a larger footprint than Cree’s XP family and also offers the unique combination of very high efficacy at very high drive currents. At 2 A, an XM LED produces 750 lumens at 110 lumens per watt. The thermal resistance of the XM platform is 2 degrees C per watt— an industry-leading technology breakthrough and a 350 percent improvement over Cree’s flagship XLamp XP-E LED.

Samples of the XLamp XM LEDs are available for order with standard lead times and commercial availability is targeted for Fall 2010.

[Canadian]

I apologize in advance for the odd timing of these posts. I had intended to post after work but got caught up with the realtor and was running around all night until going to bed. Now I'm awake in the middle of the night so I thought I'd do something "productive"

First I think you are being overly critical of my light fixture. I would not call it low quality but about a middle of the road one. Sunlight Supply makes good fixtures and these were not much different then the first generation Tek fixtures in terms of lighting output. Slightly better reflectors and active cooling would improve it somewhat but how much do you think that would be? 10%? 20%?

Nope. It's low end. For comparison here is a picture with PAR values for a higher quality T5 fixture. Keep in mind the setup here is still far from ideal given that the fixture doesn't extend the length of tank so keep your eye on the PAR values in the middle of the tank. In this picture you're seeing similar PAR values to your LED fixture with newer lamps and better quality fixture.

Secondly, while the bulbs were old, the only references I could fine say that T5s lose about 10% output over 2 years. The problem for reef tanks is the shift in colour which can lead to undesirable algae etc. But let's say that the degradation was 20% for the sake of argument. So my 300 PAR with the T5s could mean 375 PAR with new bulbs. Still much less than 500 PAR with the LEDs higher above the tank then the T5s were.

Here are PAR values on that same tank one month after the above. This hobbyist measured 20-30% PAR drop WITH ACTIVE COOLING over the course of 6 months. After driving up the fan voltage he was able to cool the fixture enough to keep the drop to 10% over 6 months. So again, old lamps on a low quality fixture (without active cooling) will show 30% + PAR drop over the course of 15 months.

Argue all you want but however you set up my test, new bulbs or not etc. my LEDs handily outperform my T5s. That's all I am claiming.

No arguing. Just trying to ensure there's a reasonable comparison without making hugely inaccurate leaps in assumptions. As shown above, your PAR values are hardly representative of a good T5 setup. And while you claim the comparison is only to your T5s you're trying to report the values as if they're some how representative of T5s by commenting on the relative quality of your fixture and expected drop in PAR of T5 lamps.

Dr. Joshi is an engineer and has been testing all sorts of lights, especially MH, for a long time so I would consider him a good independent reviewer. Here's also a more recent review of a top of the line LED fixture, the AquaIllumination:

http://www.advancedaquarist.com/2007...searchterm=PAR

This one clearly shoes the AI unit outperforming a 250W MH unit. Granted, the MH ballast used may not be top of the line but is probably typical of one used by many people.

I'm well aware of the article. It is quite dated. And again, the comparison is to a 250W 20,000K bulb on a crappy Coralife ballast with an uknown "polished aluminum parabolic reflector". At least you're recognizing that the parameters of the comparison aren't exactly even here.

With respect to who has the biggest PAR; really, who cares. Stoney corals appear to photosaturate between 400 and 500 PAR so having 700 or 1000 PAR is probably pointless other than for bragging rights. I doubt it will do the corals much good.

FWIW, I agree. This was only commented on because Steve got involved in the conversation and has, in the past, made a big deal about the high PAR values he got with his DIY MH setups on his SPS tanks when comparisons to T5s were made. Now that LED PAR values in a typical setup (such as yours) seem to be similar to those of "good" quality T5 setups (see pictures above) he seems to be suggesting those PAR values are now acceptable.

As for longevity and degradation of LEDS, that is fairly well established. While high powered LEDs are fairly new to our hobby they have been around for a decade and are well tested. Low power LEDs have been around far longer then that so the degradation of LEDs is well understood.

With respect to PAR? Please show me the data.

[StirCrazy]

Originally Posted by Canadian

With respect to PAR? Please show me the data.

Andrew, PAR is a function of spectrum and intensity, if you spectrum shifts and your intensity stays the same the PAR changes, if the intensity changes and the spectrum stays the same the PAR changes. with the LED the spectrum is the same through out the life, but like said befor at 50000 hours they will have a 15% decrease in intensity, so the PAR will drop about 15%. With the bulbs we are using now there is a intensity drop and a spectrum cange so the PAR drop can be compounded. I'll see if I can find the article I was reading about it. It comes from the glrow light side of the industry but same concerns, PAR, spectrum, intensity. this industry has had LEDs for over 10 years already, they just didn't have enough punch for coral, but they grew tomatos pretty good aparently.

Steve

[Canadian]

Originally Posted by StirCrazy

Andrew, PAR is a function of spectrum and intensity, if you spectrum shifts and your intensity stays the same the PAR changes, if the intensity changes and the spectrum stays the same the PAR changes. with the LED the spectrum is the same through out the life, but like said befor at 50000 hours they will have a 15% decrease in intensity, so the PAR will drop about 15%. With the bulbs we are using now there is a intensity drop and a spectrum cange so the PAR drop can be compounded. I'll see if I can find the article I was reading about it. It comes from the glrow light side of the industry but same concerns, PAR, spectrum, intensity. this industry has had LEDs for over 10 years already, they just didn't have enough punch for coral, but they grew tomatos pretty good aparently.

Steve

And you're assuming that with whatever installation method you choose for heatsinks and whatever you choose to drive the emitter at there will be negligible thermal damage. Again, and again I say this: theory is great when you don't have real data. We can assume there will be little intensity drop but until we see long term data, especially for the blue emitters that are more prevalent in our hobby, it's just an assumption.