Why isn't UV used as a light source?

[strich]

I've been thinking about the details of reef lighting and how it tries to replicate the real world, and I was left wondering why UV wavelengths (350nm) aren't present in reef lighting? I understand that at certain levels UV is destructive, hence the use of UV in filtration at high wattage levels to destroy diseases etc. But wouldn't a small amount of it be a net benefit as part of the light source across the tank too? Has anyone done tests on this?

 

[gbroadbridge]

I've been thinking about the details of reef lighting and how it tries to replicate the real world, and I was left wondering why UV wavelengths (350nm) aren't present in reef lighting? I understand that at certain levels UV is destructive, hence the use of UV in filtration at high wattage levels to destroy diseases etc. But wouldn't a small amount of it be a net benefit as part of the light source across the tank too? Has anyone done tests on this?

UV is dangerous and you don't want it shining on the tank.

Looking at a light fitting or reflected light from the water surface could for instance contribute to the development of cataracts and vision loss.

 

[Doctorgori]

Cancer risk might be one reason

 

[strich]

UV is dangerous and you don't want it shining on the tank.

Looking at a light fitting or reflected light from the water surface could for instance contribute to the development of cataracts and vision loss.

Cancer risk might be one reason

There is the potential for danger for sure, and to be respected, but it would seem managable. For instance, UV-A (315-400nm) seems to have well understood regulations and guidelines for healthy use.

Note: Only on posting this thread I've uncovered other similar discussions here. I will continue reading on the topic!

 

[LovinlifeinGuam]

I've been thinking about the details of reef lighting and how it tries to replicate the real world, and I was left wondering why UV wavelengths (350nm) aren't present in reef lighting? I understand that at certain levels UV is destructive, hence the use of UV in filtration at high wattage levels to destroy diseases etc. But wouldn't a small amount of it be a net benefit as part of the light source across the tank too? Has anyone done tests on this?

Metal halides actually emitted so much true UV light that they had limitations regarding depth of the corals and other issues. I don't think there is any true benefit you'd achieve but definitely possible hazards.

 

[JustMarks]

I've been thinking about the details of reef lighting and how it tries to replicate the real world, and I was left wondering why UV wavelengths (350nm) aren't present in reef lighting? I understand that at certain levels UV is destructive, hence the use of UV in filtration at high wattage levels to destroy diseases etc. But wouldn't a small amount of it be a net benefit as part of the light source across the tank too? Has anyone done tests on this?

UV does no good to your tank

 

[strich]

Metal halides actually emitted so much true UV light that they had limitations regarding depth of the corals and other issues. I don't think there is any true benefit you'd achieve but definitely possible hazards.

Re whether UV has any true benefit - I'm afraid that's not what my research so far has turned up. In short: Its no more or less beneficial than other areas of the spectrum in the most general sense. Some research suggests some minor benefits. But personally I'm more curious about the visible fluorescent expressing ability of UV at 360-380nm, which will certainly be more vibrant and more importantly, less crap blue everywhere.

 

[LovinlifeinGuam]

In shallow depths (like the typical aquarium) increased UV rays can be detrimental. There's simply no reason for adding true UV light imo. I believe UV radiation also raises the risk of bleaching if temperatures increase. That might require wavelengths lower than 350nm (I'm not sure), but I don't think I'd risk it...what is there to gain that you have read about?

 

[LovinlifeinGuam]

Re whether UV has any true benefit - I'm afraid that's not what my research so far has turned up. In short: Its no more or less beneficial than other areas of the spectrum in the most general sense. Some research suggests some minor benefits. But personally I'm more curious about the visible fluorescent expressing ability of UV at 360-380nm, which will certainly be more vibrant and more importantly, less crap blue everywhere.

Why not try it out? At those wavelengths, it wouldn't be difficult to find an affordable light for a test?

 

[strich]

In shallow depths (like the typical aquarium) increased UV rays can be detrimental. There's simply no reason for adding true UV light imo. I believe UV radiation also raises the risk of bleaching if temperatures increase. That might require wavelengths lower than 350nm (I'm not sure), but I don't think I'd risk it...what is there to gain that you have read about?

The annoying thing about this topic is that whenever anyone says "UV" and makes an opinion about it, they're covering the entire UV-A to UV-C spectrum spanning 100-400nm, which goes from destroying your eyes and skin to not really a problem hah. So don't be so quick to believe words on the positive or negative effects.

A study here discusses potentially positive effects of low amounts UV-A/UV-B (300-400nm) on corals causing them to be more hardy against swinging water conditions. Though I haven't read it in detail.

For me my goal is this: I really dislike the blue washed look of many reef aquariums. But of course a pure white setup misses out on those amazing fluorescent colour expressions across a wide range of critters. I am very curious to see if one can hit that barely visible high-UV range of 350nm to hit the peak fluorescence as well as minimise visible purple/blue light wash across the tank.

 

[Alexraptor]

You don't need UV to eliminate the blue-wash, you just need the right LED's and color balance.

This is my 15g mixed reef, with a Maxspect Jump 65W LED (Non-blue model), with all color channels at 100% intensity and a diffusor. Only the white paint and mortar of the wall gives any indication of a blue tone.

 

[strich]

You don't need UV to eliminate the blue-wash, you just need the right LED's and color balance.

This is my 15g mixed reef, with a Maxspect Jump 65W LED (Non-blue model), with all color channels at 100% intensity and a diffusor. Only the white paint and mortar of the wall gives any indication of a blue tone.

It looks great, to be sure. But I think you misunderstood my goal a little: fluorescence expression is richest at around 350nm give or take. Those lights have a couple 390nm LEDs. I'm very curious as to what difference in vibrance some LEDs at around 350-360nm would make.

 

[LovinlifeinGuam]

The annoying thing about this topic is that whenever anyone says "UV" and makes an opinion about it, they're covering the entire UV-A to UV-C spectrum spanning 100-400nm, which goes from destroying your eyes and skin to not really a problem hah. So don't be so quick to believe words on the positive or negative effects.

A study here discusses potentially positive effects of low amounts UV-A/UV-B (300-400nm) on corals causing them to be more hardy against swinging water conditions. Though I haven't read it in detail.

For me my goal is this: I really dislike the blue washed look of many reef aquariums. But of course a pure white setup misses out on those amazing fluorescent colour expressions across a wide range of critters. I am very curious to see if one can hit that barely visible high-UV range of 350nm to hit the peak fluorescence as well as minimise visible purple/blue light wash across the tank.

I skimmed through a few scientific publications...here's one of them that directly supports my previous statement. I'm sure there are others that disagree and others that agree with the one I've linked here though. And I saw you specified 350nm in your post so I didn't clump all UV wavelengths together.
At a wavelength of 333nm (pretty close to 350nm they noticed detrimental effects.

https://link.springer.com/article/10.1007/s00338-012-0927-7

 

[strich]

I skimmed through a few scientific publications...here's one of them that directly supports my previous statement. I'm sure there are others that disagree and others that agree with the one I've linked here though. And I saw you specified 350nm in your post so I didn't clump all UV wavelengths together.
At a wavelength of 333nm (pretty close to 350nm they noticed detrimental effects.

https://link.springer.com/article/10.1007/s00338-012-0927-7

You can download the full paper here. I had a read through it and it was pretty interesting, thanks! For the purposes of our discussion however it's difficult to apply: In this paper they replicate the real world PAR the coral was harvested from and run a test with additional UV (315-340nm). The outcome is as you summarise, that it causes the coral to spend more time producing the MAA required to sunscreen itself at the expense of growth. AFAIK we would not get close to pushing the same amount of PAR in our home systems as to even a normal sunlit day let alone a sunny day + more UV, so I would guess we would see no negative consequences at home.

It's worth noting that their zero-UV experiment presented with the most growth of all. I don't know if that again relies on there just being a lot of UV via sunlight vs a tiny 6W UV LED, or if literally any <400nm light causes the coral to spend more time producing MAA sunscreen.

 

[LovinlifeinGuam]

You can download the full paper here. I had a read through it and it was pretty interesting, thanks! For the purposes of our discussion however it's difficult to apply: In this paper they replicate the real world PAR the coral was harvested from and run a test with additional UV (315-340nm). The outcome is as you summarise, that it causes the coral to spend more time producing the MAA required to sunscreen itself at the expense of growth. AFAIK we would not get close to pushing the same amount of PAR in our home systems as to even a normal sunlit day let alone a sunny day + more UV, so I would guess we would see no negative consequences at home.

It's worth noting that their zero-UV experiment presented with the most growth of all. I don't know if that again relies on there just being a lot of UV via sunlight vs a tiny 6W UV LED, or if literally any <400nm light causes the coral to spend more time producing MAA sunscreen.

In complete honesty, I think you should experiment with it...why not? It would be interesting!

 

[ca1ore]

Some of the LED lights available for reef tanks touch the high end of the UV spectrum. Reefi, for example, says they use a 395/400 nm UV channel. Radion and Maxspect also.

 

[strich]

Some of the LED lights available for reef tanks touch the high end of the UV spectrum. Reefi, for example, says they use a 395/400 nm UV channel. Radion and Maxspect also.

Yeah indeed. I've found a few brands that have a few 365nm LEDs in them too. However were I to test this I think I would go buy a dedicated 315-340nm spot or strip light. I am dang curious about this hah.