Where did the light go??????

[Coralmex]

I recently decided to change my 4 - 250 watt Aqualine HQI bulbs which had been in use for 16 months... I also wanted to switch from a 10K bulb to a 20K bulb...

However when I change the 2 inner lamps in the 4 lamp row the "Quantity" of light appeared to be a huge amount less than the 2 "old" 10 K bulbs...

I know the 20K is a much bluer spectrum..... But am I still generating the same QUANTITY of light???

The new bulbs are XM 250 watt HQI 20K..... My ballasts are PFO brand....

[superedge88]

20k bulbs are natorious for having low PAR. While you still have a 250 watt bulb in, you are not going to get the same amount of PAR out of these bulbs compared to the 10k. Best to do research on different bulb brands and spectrums before you purchase so that you can make sure that you are getting the best bulb for your corals and a color temp of your liking.

[Coralmex]

Superedge88,

When you talk about PAR.... IS that the equivalent of "Spectral Irradianance" that Sanjay measures on his plots???

[superedge88]

Good question, I don't believe it's the same thing. I believe they are very similar, I believe that PAR is spectral irradiance within 400-700nm. Someone else will probably chime in and correct me if I'm wrong.

[Sanjay]

<a href=showthread.php?s=&postid=7089150#post7089150 target=_blank>Originally posted</a> by Coralmex
Superedge88,

When you talk about PAR.... IS that the equivalent of "Spectral Irradianance" that Sanjay measures on his plots???

Your should read this:

http://www.reefkeeping.com/issues/2006-03/sj/index.php

If you still have questions.. I'll be glad to answer them.

As for you question.. yes, you will get low PPFD from the 20KK lamps compared to the 10K. Also, your eyes will percieve the blue light as being a lot less. You can read about that in the next issue of my lighting series, the April issue that will be out soon.

sanjay.

[mwood]

You may want to look into pheonix or aquaconnect bulbs. A little better par and 14k look. You might like it better. Plenty of pics around RC if you want to go looking.