question about different bulbs

[xtopher]

I was just looking at sanjay joshi's spectral analysis on differnt bulb types but it still left a question unanswered. If switching from 10k to 20k are the corals still recieving the same "quality" of light? I know that the spectrum changes but what about par/lux do they remain the same? I am thinking of switching to a higher kalvin bulb but am wondering if the wavelength will still be sufficient for mid level sps, or will I have to upgrade to 400watt lighting. These are being run by HQI ballasts at the moment.
Thanks
Chris

[Geoff]

take a look at the PAR readings this gives you a good indicator of the amount of light the corals will be using for food. in most cases as you go up in K you will go down in PAR. there are a few that do not go down that much. the XM 20K for example.

G~

[xtopher]

Thanks G

[Cyberdude47]

Chris
When using Sanjays website Use the PPFD (Photosynthetic Photon fux density) figures to find intensity. as an example to compare a 250 HQI XM 10K (109 PPFD) to a 250 HQI XM 20K (49 PPFD) you'll find that it is under half the intensity but if you upgrade to a 400 watt single ended lamp XM 20K (128 PPFD) (with a magnetek ballast, other ballast don't perform quite as well) you'll see that it's about 15% brighter