In the last month or so I've read all of Sanjay's articles at Advancedaquarist.com, and all of Dana Riddle's articles there too. Nearly all of the topics and graphics that Sanjay covered in his talk (except the comments about his own tank) can be found within those articles, along with information that Sanjay had to skip over due to time constraints.
Dana's articles also go into good depth about lighting other than MH, and Dana also provides very good information about the spectrum and intensity of the light landing on our corals when they are in the wild.
The guy who was at the meeting who is a collector in Florida, I'm sorry I'm not certain of his name, made a valuable point about how most of the acropora he was collecting came from deeper than 60 feet. While diving in Fiji I noticed most of the colorful acroporas were at 25-60 feet. LiveAquaria's coral listings often include their collection depth as 20+ feet.
This information synch's well with Sanjay's comments about the light intensity in his own tank (I'm sure it's dimmer than most people would have expected). I was the one who answered Sanjay's question about the intensity of the light at the surface of the ocean-about 2000 micro whatevers. Well, at 20 feet deep it's about 400-500, which is what the VHO tank picture Sanjay displayed was measured at, and I suspect close to the intensity in Sanjay's tank.
Dana's articles also show spectrum graphs and the spectrum at about 25 feet is very similar to the spectrum of a URI actinic or some of the T5 blues. In the MH arena, you'd have to get one of the "bluest" lamps to get near that, which IIRC, is what Sanjay uses in his tank.
I bought a little spectrometer for about $30 from a place that Dana recommends and with it I can see the spectral output of lamps (not a graph), and I can put a camera up to the eyehole and get a photo of the spectrum. I use all VHO's, and I intend to compare the photos of a new lamp with ones of various ages to give me some hints about their spectral changes over time. People could do the same with any lamp.
Article about the device...
http://www.advancedaquarist.com/2006/7/aafeature
It's the "plastic spectrometer" that I bought here...
http://www.starlab.com/psprod.html
I think some people, like Dana would disagree a little with Sanjay when he says that PAR is essentially the same as PUR because they measure so similarly. He showed the graph of the Favia coral's use of the various ranges of the light spectrum. The Favia is somewhat unique among corals in how it uses light and other "experts" in the hobby have made this point.
Sanjay did show a graph of the fairly tight ranges of light that the zoox in most, but not all corals prefer. Blue is the most used, then red, then some of the purple and green ranges. Dana's lab measurements indicate that too much red can cause photoinhibition more easily than too much of other color ranges.
One could say that the coral doesn't really need the other ranges (yellow, orange, etc.) so a measurement of PUR (measures the small'ish ranges most used by most corals) could be different from PAR (measures all ranges as one). Dana's articles talk about this.
But like Sanjay mentioned, most people want the lamp that helps their corals AND looks good to their own eyes, so the preferred lamp is often a compromise for these two needs.
It sounds like Sanjay's presentation has set a very high standard for the club's presentations. Future presenters will have a hard act to follow!
Dana's articles also go into good depth about lighting other than MH, and Dana also provides very good information about the spectrum and intensity of the light landing on our corals when they are in the wild.
The guy who was at the meeting who is a collector in Florida, I'm sorry I'm not certain of his name, made a valuable point about how most of the acropora he was collecting came from deeper than 60 feet. While diving in Fiji I noticed most of the colorful acroporas were at 25-60 feet. LiveAquaria's coral listings often include their collection depth as 20+ feet.
This information synch's well with Sanjay's comments about the light intensity in his own tank (I'm sure it's dimmer than most people would have expected). I was the one who answered Sanjay's question about the intensity of the light at the surface of the ocean-about 2000 micro whatevers. Well, at 20 feet deep it's about 400-500, which is what the VHO tank picture Sanjay displayed was measured at, and I suspect close to the intensity in Sanjay's tank.
Dana's articles also show spectrum graphs and the spectrum at about 25 feet is very similar to the spectrum of a URI actinic or some of the T5 blues. In the MH arena, you'd have to get one of the "bluest" lamps to get near that, which IIRC, is what Sanjay uses in his tank.
I bought a little spectrometer for about $30 from a place that Dana recommends and with it I can see the spectral output of lamps (not a graph), and I can put a camera up to the eyehole and get a photo of the spectrum. I use all VHO's, and I intend to compare the photos of a new lamp with ones of various ages to give me some hints about their spectral changes over time. People could do the same with any lamp.
Article about the device...
http://www.advancedaquarist.com/2006/7/aafeature
It's the "plastic spectrometer" that I bought here...
http://www.starlab.com/psprod.html
I think some people, like Dana would disagree a little with Sanjay when he says that PAR is essentially the same as PUR because they measure so similarly. He showed the graph of the Favia coral's use of the various ranges of the light spectrum. The Favia is somewhat unique among corals in how it uses light and other "experts" in the hobby have made this point.
Sanjay did show a graph of the fairly tight ranges of light that the zoox in most, but not all corals prefer. Blue is the most used, then red, then some of the purple and green ranges. Dana's lab measurements indicate that too much red can cause photoinhibition more easily than too much of other color ranges.
One could say that the coral doesn't really need the other ranges (yellow, orange, etc.) so a measurement of PUR (measures the small'ish ranges most used by most corals) could be different from PAR (measures all ranges as one). Dana's articles talk about this.
But like Sanjay mentioned, most people want the lamp that helps their corals AND looks good to their own eyes, so the preferred lamp is often a compromise for these two needs.
It sounds like Sanjay's presentation has set a very high standard for the club's presentations. Future presenters will have a hard act to follow!
