Ahhhh...lighting, one of my favorite subjects.
Does 10k really offer a "better" par for coral growth?
It depends on the brand of bulb as far as PAR. Many thing influence coral growth besides lighting, but if the conditions in 2 tanks were exactly the same except for lighting, the tank with more PAR "should" have better coral growth....depending on the type of coral. Some don't like lots of light.
When I am looking at bulbs, I use Sanjay Joshi's Lighting site
. Sanjay tested hundred of different MH
bulbs and the results are posted there. Keep in mind, he tested all the bulbs out of water with no reflector, but if with your particular tank setup and reflectors, you lose for example 20% of the output, you will lose 20% on every bulb.
Here are the Performace Results
for all 250w MH
bulbs tested. When you look at the chart, look at PPFD (Photosynthetic Photon Flux Density) which is the basically amount of usable light for coral the bulb puts out and CCT (Correlated Color Temperature) which is the actual K
temp of the bulb as tested.
You use Coralvue ballasts, which are similar to IceCap ballasts, so as an example, here the difference is a few SE bulbs all run with an IceCap ballast.
Your current bulb - Coralvue 15K: 47 PPFD
Coralvue 10K: 86 PPFD
XM 15K: 47 PPFD
XM 10K: 115 PPFD
10K: 90 PPFD
Aquaconnect 14K: 83 PPFD
I use 3 175w Iwasaki 15K over my 6' 125. They are 86 PPFD, so basically I am using less electricity and getting more PPFD than many 250's.