LED’s- No UV? Do corals need UV for longterm health?

[Randy Holmes-Farley]

Completely agree, personally though, I think the best approach is baseline first (natural environment),

I do not disagree that the natural environment is a decent baseline for most types of experiments, but defining natural light is not simple. It is quite depth dependent, and also strongly relates to what is suspended and dissolved in the water.

This article shows that UV-B drop by 90% can happen in as little as 9 cm, or 16 m, depending on the local water conditions.

https://onlinelibrary.wiley.com/doi/abs/10.1562/2005-11-09-IR-733

 

[rossco]

Let us observe @rossco tank. He was doing something right with lighting. I know exactly what he was doing and I’ll list it below. Always the Metal Halide tanks that impress me. The quality of light is top notch.

Thank for the tag! I really miss that tank.

My new tank is doing well with Radions plus a couple blue plus T5’s, but there was nothing like Radiums with VHO actinic for overall coral grown and health.

I get decent growth now, but still have sporadic die offs for no good reason. Never did with that tank - obviously.
maybe the overall coral health was just better under that light? Who knows.

If it were not for the heat and extra energy consumption generated by both the bulbs themselves and the chiller I had to run, I would still be using them.

 

[JNalley]

I do not disagree that the natural environment is a decent baseline for most types of experiments, but defining natural light is not simple. It is quite depth dependent, and also strongly relates to what is suspended and dissolved in the water.

This article shows that UV-B drop by 90% can happen in as little as 9 cm, or 16 m, depending on the local water conditions.

https://onlinelibrary.wiley.com/doi/abs/10.1562/2005-11-09-IR-733

Yes, and UVC is mostly filtered out by the Ozone layer. The shorter the wavelength, the easier it is to filter out. This is the same with all waves such as radio. The longer the wavelength, the more penetration power it has. That being the case, we know that UVA (315-380nm) has more penetrating power than UVB (280-315nm). So less filtration of UVA occurs with water conditions and more UVA is able to reach the corals than UVB in any given situation. Just as 2.4GHz wireless can reach further than 5GHz wireless and isn't obstructed by walls nearly as bad as 5GHz is. Both spectrums likely matter in the grand scheme of things (UVA/UVB), however, we're not at a point yet where adding UVB to a light is economical, and since we know the effects of UVC and higher frequency UVB on bacterial organisms, I would be leary about adding certain wavelengths to it without more data anyways. But getting long-term spectral analysis of reef environments at different depths would go a long way in providing us with data to average out a good spectrum of "natural light" that we can use as our baseline, just as has been done with long-term water chemistry analysis.

 

[Reefahholic]

Thank for the tag! I really miss that tank.

My new tank is doing well with Radions plus a couple blue plus T5’s, but there was nothing like Radiums with VHO actinic for overall coral grown and health.

I get decent growth now, but still have sporadic die offs for no good reason. Never did with that tank - obviously.
maybe the overall coral health was just better under that light? Who knows.

If it were not for the heat and extra energy consumption generated by both the bulbs themselves and the chiller I had to run, I would still be using them.

@rossco old tank for anybody that missed it. He had a little bit of Growth in there. HaHa!

 

[damsels are not mean]

I would be leary about adding certain wavelengths to it without more data anyways. But getting long-term spectral analysis of reef environments at different depths would go a long way in providing us with data to average out a good spectrum of "natural light" that we can use as our baseline, just as has been done with long-term water chemistry analysis.

I think the danger with rushing into UV lighting is that there are too many unknowns. First off, much of the light might be absorbed by other things in the water column. Water itself may only filter a certain amount, but there's a whole lot in the ocean that isn't in our tanks, and we don't even fully understand what's in our tank water organically speaking. Another problem is being able to apply these things we learn to many tanks. Maybe we can find out how much UVA and B corals need or want, but can we reliably reproduce that spectrum with our hobby-grade equipment and measuring tools? What equipment/settings produce that spectrum in hobbyist X's tank won't necessarily do the same for Y's tank. And Z's tank might get totally cooked by it.

Are our corals not colorful enough? I would hate to see a tank full of healthy and massive SPS colonies turn into a fresh batch of live rock.

 

[J1a]

I think the danger with rushing into UV lighting is that there are too many unknowns. First off, much of the light might be absorbed by other things in the water column. Water itself may only filter a certain amount, but there's a whole lot in the ocean that isn't in our tanks, and we don't even fully understand what's in our tank water organically speaking. Another problem is being able to apply these things we learn to many tanks. Maybe we can find out how much UVA and B corals need or want, but can we reliably reproduce that spectrum with our hobby-grade equipment and measuring tools? What equipment/settings produce that spectrum in hobbyist X's tank won't necessarily do the same for Y's tank. And Z's tank might get totally cooked by it.

Are our corals not colorful enough? I would hate to see a tank full of healthy and massive SPS colonies turn into a fresh batch of live rock.

Great points!

I think with the advancement in the LEDs, UVA leds are certainly becoming more accessible to hobby grade applications. We are not there yet, but well could be.

And to measure the UV radiations, we need to look beyond just the Par value, and start to consider taking measurements into UV spectrum.

Will it improve coral growth and color? The only way to find out, is to experiment with it. And this is something I'm very keen to do.

 

[Dana Riddle]

Let's not forget that metal halide lamps, at least some of them, could produce UV-A (the mercury spike at 365nm) and some UV-B. I looked at the UV thing at the coral farm back in the 90s.

 

[jda]

14k Phoenix, 20k Radium on m80 (250w - the real one, and not the 400w one) and the newer 20k Hamilton all have output from 350nm up. The LiCor that I borrowed read down to 300/310, I think, and there was not much below 350nm (360nm, really). For the 14k Phoenix, I used the tempered glass shield in the fixture. For the SE bulbs from Radium and Hamilton, just the bulb with the built-in glass. The UV is getting in the tank. The new Hamilton really stopped after 850/900nm which really cut back on the heat, BTW. The dual arc bulbs from RB or the new line of Hamilton bulbs are only a few years old and were designed to be more efficient, less heat and are probably newer tech than most white or RB diodes in new panels today. If you really want a fair comparison, these need tested today, not based on lights of the past. Would it be smart to test LEDs from the 90s either?

Daylight bulbs are going to differ a bunch, which is mostly what I fear was being tested in the 1990s. MV, HPS and even MH in the 1990s are not quite what they are today and I would pay attention to some of Tullio's, Sanjay or others testing of bulbs that people use over nearly anything done in the 1990s. Our tank water is clear enough and with shallow enough depth that you can bet that some UV (and IR, which I find also important) is getting to the corals.

This is some of Dr. Joshi's work with Radium 20k on real m80 (correct ballast). 6500k reef bulb also in there, which is not the same as some Ag or GP bulbs used early on. reefs.com/lighting has Dr. Joshi's plots, but you need to change the range down to 350nm to see the UV.

Until somebody can explain to me in a rational and lucid way why light sources missing UV and IR are not "not as good" as sources with, then don't we have to assume that they matter? I am not talking about preference stuff like perceived heat issues, apps and thunderstorms, form factor, but pure, actual performance over corals that people miss even if they don't use sources with UV and IR anymore. You see these posts all of the time where people talk about what they like about their new lights and then mention that they are not at the level of performance that their older lights were.

 

[Reefahholic]

 

[Reefahholic]

@Dana Riddle I’m starting to think that this is why Halides grow corals so well. They seem to have more UV than all the other lights.

This definitely needs to be investigated more before we all jump to conclusions. ;Pompus

 

[jda]

IR too. There is some evidence that Emerson Effect is real.

We have no real science on this that actually equates perfectly... just innuendo from similar studies or some on one particular coral that could be picked at for applicability, but still fun to read and learn. ...so we have to just use anecdotes and supposition.

 

[GoVols]

Let's not forget that metal halide lamps, at least some of them, could produce UV-A (the mercury spike at 365nm) and some UV-B. I looked at the UV thing at the coral farm back in the 90s.

Dana,
Are we ever going to be able to get leds to match halide’s specs?

 

[outhouse]

@Dana Riddle I’m starting to think that this is why Halides grow corals so well. They seem to have more UV than all the other lights.

This definitely needs to be investigated more before we all jump to conclusions. ;Pompus

Well I'm adding 2 uv light bars to my limited spectrum, with 1 I can tell you hammers are all loving it. BTAs need more acclimation but still loving it

 

[damsels are not mean]

@Dana Riddle I’m starting to think that this is why Halides grow corals so well. They seem to have more UV than all the other lights.

Do halides grow coral better than LEDs? I am not convinced the limiting factor in coral growth is lighting in any home aquarist's system. And even if it were, is there really a (positive) difference in favor of halides? I have been out of the loop for a while so I don't know if any quantitative comparisons have been made in this hotly debated topic.

 

[Dana Riddle]

Dana,
Are we ever going to be able to get leds to match halide’s specs?

BuildMyLED (now Fluence Bioengineering) produced a strip years ago that that mimicked a 20K Radium. Visually, it appeared close, but spectral analyses showed major portions of the spectrum were missing. I'm not saying their lights are bad, just different from metal halides. I haven't spoken with Nick much after he sold the business. I'll try to get in touch with him. As far as intensity, even some of the black boxes produce too much light and should be operated in a fraction of their potential output.

 

[Dana Riddle]

As soon as I get my late Mom's estate settled, I'll get back in the lab and crank up the fluorometer. Iwasaki sent me some engineering sample lamps (an improved daylight MH). It would be fun to look at the electron transport rates under different sources, but at the same PPFD. I'll use Apogee's new ePAR sensor.

 

[jda]

I know that you did not ask me, but making LED act and look like MH would take away most of their real, and perceived, value-add. True UV LEDs are short lived, ruin lenses and need replaced probably faster than MH bulbs do - you could make sockets and replace them, but then the value-add about not replacing bulbs is gone. Glass lenses could be used on UV LEDs, but another expense and the LEDS themselves would still need replaced. Using IR would add heat. Many would soon realize that this is mostly a bogus argument since most heat is easily managed if you want to, but the talking point is gone. Both would use more power in a realm where there is not really much power savings anyway as long as you are not choosing way too much of one kind or another. In the end, the people who want all of this stuff probably just would use a Halide anyway, so is there enough of a market share to mess with it? Most people who go to an online site or LFS and buy a LED don't know lighting from shineola.

I don't know that anybody has figured out how to beat the reflector with an LED. I mostly have larger tanks, so my experience is with those and I admittedly have little experience or interst in smaller, shallower tanks or nanos, but you need at least 250w of LED to replace a 250w Halide for my acropora and clams, so if you had to reflect that LED the spread would be a tremendous improvement, but the efficiency would go down. They are already pretty much equal on wattage in the real world on tanks like mine. I have not yet seen any good answers for a reflector. The best that I have seen is wide panels way up high where the light blends better, but there is still shadowing beyond what reflectors have - like a Photon V2 the way that therman uses them, for example.

 

[Dana Riddle]

I know that you did not ask me, but making LED act and look like MH would take away most of their real, and perceived, value-add. True UV LEDs are short lived, ruin lenses and need replaced probably faster than MH bulbs do - you could make sockets and replace them, but then the value-add about not replacing bulbs is gone. Glass lenses could be used on UV LEDs, but another expense and the LEDS themselves would still need replaced. Using IR would add heat. Many would soon realize that this is mostly a bogus argument since most heat is easily managed if you want to, but the talking point is gone. Both would use more power in a realm where there is not really much power savings anyway as long as you are not choosing way too much of one kind or another. In the end, the people who want all of this stuff probably just would use a Halide anyway, so is there enough of a market share to mess with it? Most people who go to an online site or LFS and buy a LED don't know lighting from shineola.

I don't know that anybody has figured out how to beat the reflector with an LED. I mostly have larger tanks, so my experience is with those and I admittedly have little experience or interst in smaller, shallower tanks or nanos, but you need at least 250w of LED to replace a 250w Halide for my acropora and clams, so if you had to reflect that LED the spread would be a tremendous improvement, but the efficiency would go down. They are already pretty much equal on wattage in the real world on tanks like mine. I have not yet seen any good answers for a reflector. The best that I have seen is wide panels way up high where the light blends better, but there is still shadowing beyond what reflectors have - like a Photon V2 the way that therman uses them, for example.

Orphek uses glass lenses on their shortwave LEDs.

 

[ATXreefer]

As soon as I get my late Mom's estate settled, I'll get back in the lab and crank up the fluorometer. Iwasaki sent me some engineering sample lamps (an improved daylight MH). It would be fun to look at the electron transport rates under different sources, but at the same PPFD. I'll use Apogee's new ePAR sensor.

Kind of shocking they're still developing these lamps with (what I perceive as) such little market share! Maybe with improved efficiency they could make some sort of sustained "comeback".

 

[Dana Riddle]

Kind of shocking they're still developing these lamps with (what I perceive as) such little market share! Maybe with improved efficiency they could make some sort of sustained "comeback".

I'll check and see if these lamps were ever released. It would be a waste of my time to test a lamp that isn't available. But with that said, the Iwasaki DL MH lamps have a proven track record.