UV with T5s

[LadyTang2]

Do T5s put out much UV :cool:? When I look at most of the T5s from ATI they basically dont go much below 400.

I am looking at reefbreeders LED strip (blue/uv hybrid) which includes 380nm LEDs. Would this be helpful since it looks like not much comes from T5s below 400?

 

[Daniel@R2R Verified Admin]

bump for you #lightinggurus @Dana Riddle

 

[Dana Riddle]

Chlorophyll a can absorb some UV-A radiation and use it in photosynthesis. Some fluorescent proteins can absorb it and fluoresce. UV-A can promote production of some coral colors as well.

 

[Variant]

Chlorophyll a can absorb some UV-A radiation and use it in photosynthesis. Some fluorescent proteins can absorb it and fluoresce. UV-A can promote production of some coral colors as well.

Dana, would UV also help convert proteins into certain vitamins that aid in calcification? I vaguely recall how UV aids in the production of vitamin D for humans and how it helps to regulate proper calcification.

 

[oreo54]

Do T5s put out much UV :cool:?

No.

 

[Dana Riddle]

No.

Mercury will emit radiation at 365 nm when excited.

 

[LadyTang2]

Thanks, aside from UV, what other areas of lighting do T5s lack in? I don't mean ease of use or anything like that but rather the actual growth ability of the light ie no fill in the blank nanometers or something else.

 

[hart24601]

Mercury will emit radiation at 365 nm when excited.

so when we look at the factory spectrum chart is that peak just cropped off?

Oh I see it now. My mistake. Do you think that amount makes it into the tank and corals?

 

[Dana Riddle]

so when we look at the factory spectrum chart is that peak just cropped off?

If the chart doesn't go below 400nm, then yes it is cropped.

 

[hart24601]

If the chart doesn't go below 400nm, then yes it is cropped.

sorry Dana I edited my post, I looked at more graphs and some do have it if they are not cropped at 400. It looks quite small, do you think it reaches the coral in any meaningful intensity?

 

[Dana Riddle]

Thanks, aside from UV, what other areas of lighting do T5s lack in? I don't mean ease of use or anything like that but rather the actual growth ability of the light ie no fill in the blank nanometers or something else.

I don't have any UV numbers for T5 lamps, but have plenty for VHO and metal halides. Four 110w VHO lamps driven by an IceCap ballast (2 actinics and 2 actinic whites, 3.5" above the sensor with no reflector) produced 41 microWatts/cm2 UV-A and 12 microWatts/cm2 UV-B. These numbers would be much higher with an effective reflector. So, it really depends upon your definition of 'much UV', but fluorescent lamps can produce UV. In the case of aquarium lamps, most UV is absorbed by phosphors and the glass tube. If the glass formula is changed, UV-A and UV-B can be transmitted (such as in the case of UV-B lamps for use in vitamin D production in reptiles.) For comparative purposes, an Iwasaki 6500K metal halide lamp produced over 600 microWatts/cm2 UV-A and ~65 microWatt/cm2 UV-B - these numbers are much higher when the lamp is warming up.

 

[Dana Riddle]

sorry Dana I edited my post, I looked at more graphs and some do have it if they are not cropped at 400. It looks quite small, do you think it reaches the coral in any meaningful intensity?

Since most UV wavelengths cannot be sensed by the human eye, UV is best reported in radiometric units (watts, microWatts, etc.) so it is difficult to judge UV intensity when looking at spectrometer measurements. Most fluorescent lamps are shielded for UV, but some 'leaks' out. 41 microwatts/cm2 UV-A and 12 microWatts/cm2 UV-B. This isn't much when compared to the sun, but I did get a slight sunburn on my arm when I was working under actinic lamps for a couple of hours.

 

[hart24601]

Since most UV wavelengths cannot be sensed by the human eye, UV is best reported in radiometric units (watts, microWatts, etc.) so it is difficult to judge UV intensity when looking at spectrometer measurements. Most fluorescent lamps are shielded for UV, but some 'leaks' out. 41 microwatts/cm2 UV-A and 12 microWatts/cm2 UV-B. This isn't much when compared to the sun, but I did get a slight sunburn on my arm when I was working under actinic lamps for a couple of hours.

Thanks! Always appreciate your posts.

 

[oreo54]

Mercury will emit radiation at 365 nm when excited.

Operative word was much.
Normal T5's do not output much UV
Seems no more so than 410-ish leds

Mh's can produce much UV, even the shielded ones.

Of course defining much is situationally dependent :)

 

[LadyTang2]

So do you think it would be wise to seek out a LED strip that includes 380nm rather than just getting the reefbrite blue strip which does not have UV leds? My thought was the UV LEDs might bring something missing from teh T5s and help my corals.

 

[oreo54]

Operative word was much.
Normal T5's do not output much UV
Seems no more so than 410-ish leds

Mh's can produce much UV, even the shielded ones.

Of course defining much is situationally dependent :)

Need to mention water attenuation as well

 

[Dana Riddle]

Dana, would UV also help convert proteins into certain vitamins that aid in calcification? I vaguely recall how UV aids in the production of vitamin D for humans and how it helps to regulate proper calcification.

UV-B helps produce vitamin D in mammals and reptiles. I am unsure of its importance in corals.

 

[Dana Riddle]

Need to mention water attenuation as well

The very first article I wrote for Aquarium Frontiers back in the late 90's looked at UV attenuation coefficients. Let me see if I can find that data/article.

 

[oreo54]

UV-B, the frequency range of ultra-violet light that causes sunburn, is absorbed by water but you need a few metres of it to

provide adequate protection. Half a metre of water will still let 40 per cent of the UV-B through and the cooling effect of the water makes you less aware of the Sun

.

So about 40%%~ of the uv b emitted by a tube
will reach a tank bottom if it is about 1/2 meter deep

 

[Dana Riddle]

Here's data from Jerlov. Penetration of UV through a water column depends upon wavelength and 'type' of water. Jerlov classified seawater into 'oceaninc' (blue) and 'coastal' (green) waters. If your aquarium is well maintained (water changes, GAC, etc.) your water likely resembles Type I Oceanic (the 'clearest'.) Unfortunately, his data includes only UV-A at 375nm buthe found that better than 95% of UV-A @375nmwas transmitted in Oceanic Type I water.