More Lighting Talk

[Troy F]

For those of you who've read Sanjay Joshi's article in the Marine Fish and Reef 2002 Annual, what were your thoughts? One thing that stood out for me was the following exerpt: An Iwasaki 6500K lamp at a distance of 6 inches from the water can provide a PPDF close to 1600 uE/s*m2 without a reflector. Using a reflector, this value can be easily increased by another 50 to 75 percent (depending on the quality of reflector design). Surface values on reefs have been measured around 2000 uE/s*m2.

To me this reads that it is possible to out perform the sun. Could any of you lighting experts simplify, qualify or explain the above paragraph?

Another very interesting bit of information provided was how poorly most of the 10000K lamps perform compared to other equal watt lamps. Hopefully these comparisons won't drive the price of Iwasaki up but on the other hand maybe they'll drive the price on the other bulbs down.

Thoughts?

[DJ88]

Troy,

As I see it the reflectors are focusing the light being emitted by the bulbs. Theoretically you could do this with the sun as well to increase the amount of light is being measured on a specific location. Magnify the sun enough and you can start a fire.. [img]images/smiles/icon_wink.gif[/img] In an audio or radio situation this is called an amplifier. With light I call it a focusing reflector(my own creative wording [img]images/smiles/icon_wink.gif[/img]) Light is just a different wavelength in the electromagnetic spectrum and as such has the same properties as all otehrs such as audio and radio waves do. You can amplify it(or magnify in this case).

I know you know this but here is a pic for those who can't quite imagine it.. [img]images/smiles/icon_wink.gif[/img]



Put the meter where all the light is focusing and you are going to have some awesome light hitting that spot. Imagine it is a coral there.. [img]images/smiles/icon_biggrin.gif[/img] and POW!! SUPER GROWTH! As long as you get it used to all that light that is.

[reefburnaby]

Hi,

That basically sums up why I like Iwasakis.

But, the problem is that if the distance between the lamp and coral double, the PAR is reduce by 1/4 its value. Let's say the average distance between a lamp and a coral is 18inches (or triple the distance), then the PAR would be reduced by 1/9 (square of the distance) of 2000 or approx 200 uE/m^2-s.

Oceans do suffer from the same problem, so 18 inches in to the ocean does not result in adrastric drop in PAR -- the distance between the sun and the surface of the ocean is several billion times larger than 18 inches. In order to reduce normal sunlight's PAR by 1/4, we would need to double the distance between the sun and the ocean -- which would be very far away.

So, although we measure 2000uE/s-m^2 on the surface of the water in our reefs and in the ocean, the PAR is drastically different between our reefs and the ocean near 0.1 to 40 meters under the surface.

Hope that helps.

- Victor.

[ 05 January 2002: Message edited by: reefburnaby ]

[Troy F]

Darren, in the equation uE/s*m2 does the m2 not mean square meter? If they are just taking measurements from the focused point then isn't the light rating on MH vastly overrated. I think I understand what is going on here but like to hear other input.

Taking the 1600 uE/s*m2 figure from a 250W Iwasaki, what would be the comparison to a 4x110 VHO set-up (forget IceCap for a moment here)? Is the 440W of light even remotely comparible to the output of 2x250W Iwasaki? I guess you guys that are doing the testing will have some answers but I wonder why no one has done any of these tests on florescent lighting before.

[Troy F]

Victor, I posted my last somehow after your last post which wasn't there when I started typing. You've explained much of what I was wondering very well.

What would the equivelant ocean depth of 200 uE/m^2-s? By the way, why did you write the formula different than Sanjay?

[reefburnaby]

Hi,

200uE/m^2-s = 200uE/(s*m^2). Its just notation -- I just screwed up a little bit.


As for what depth does 200uE/m^2-s...it is about 30m under the surface.

From the experts:
Discovery Bay In Jamaica.
Surface = 1925 uE/(s*m^2)
15m = 392 uE/(s*m^2)

Great Barrier Reef
10m = 490 uE/(s*m^2)


FYI, these were measured independently..but...

1000 uE/(s*m^2) for 4x110W of VHO (at water surface)
1100 uE/(s*m^2) for 4x96W of PC (at water surface)

- Victor.

[Troy F]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by reefburnaby:
FYI, these were measured independently..but...

1000 uE/(s*m^2) for 4x110W of VHO (at water surface)
1100 uE/(s*m^2) for 4x96W of PC (at water surface)

- Victor.<HR></BLOCKQUOTE>

Great info Victor, you're a goddamn encyclopedia. You wouldn't happen to know what type of bulbs and the distance off the surface they were mounted would you?

[canadawest]

I also read Sanjay's article and it actually influenced a purchase decision today!

I just ordered a PFO Dual-250W MH kit with a pair of Iwasaki 6500K 250W lamps.

Interesting to note in Sanjay's article that the Iwasaki 250W lamp had a better output (higher PAR) on a MH ballast than on a MV ballast which it's supposed to run better on! (Although the opposite was true of the 400W lamp) Because of this fact I chose the MH over the MV (EYE) ballast. Also not being limited to only Iwasaki 250W lamps in future is nice too.

And another interesting tidbit to note, as Troy mentioned, was the poor performance of the 10K lamps. An Iwasaki 250W 6500K lamp is outperforming (PAR) any 400W 10K lamp!

So I'm totally stoked about adding the new lighting, and got it for so cheap I have to wonder if it fell off the back of a truck.

If anyone can guess (within $25) what I am paying, I'll let you know the guy in the US that is selling them. He's got all sorts of aquarium supplies, and at wholesale pricing.

I am getting:

1 - PFO Dual-250W MH ballast
2 - Mogul sockets
2 - 2'x2' flat polished reflectors (will shape myself)
2 - Iwasaki 6500K 250W lamps

Wooohooo!! Now all I need is to find a deal on a PM HOT-1 skimmer, and I'll be content with the tank equipment for a while longer.

[Delphinus]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by canadawest:
<snip>
If anyone can guess (within $25) what I am paying, I'll let you know the guy in the US that is selling them. He's got all sorts of aquarium supplies, and at wholesale pricing.
<HR></BLOCKQUOTE>

Sigh ... Ok, I'll bite: $300 USD?

[canadawest]

Nice guess Tony, but not even close! [img]images/smiles/icon_wink.gif[/img]

For a complete dual-250W PFO kit including the Iwasaki 6500K lamps I shopped around.

Here's what I found:
<UL TYPE=SQUARE><LI>Premium Aquatics - $334.80 + Shipping (US$)

<LI>Marine Depot - $339.00 + Shipping (US$)

<LI> J&L Aquatics - $684.00 (CDN$)[/list]
I am getting the complete setup (including shipping) for LESS THAN HALF J&L's price BEFORE taxes!

If anyone else is interested in getting MH lighting let me know, I can give you contact info for this seller.