Not Convinced of Light Intensity

[Bryan]

I am beginning to wonder if there is a lot more to coral growth than light intensity. I purchase a few montipora frags from Perkys Pets a number of months ago. I had the frags under a Ushio 10K 400 watt and the growth has actually been dismal, recently switched to the Iwasaki 250 watt and growth has picked up.

What I find surprising is the same frags at Perkys pets have literally doubled or tripled in size for the same time period. The lighting they are using is 6500K 175 watt bulbs. Kinda surprisng.

My water parameters seem okay calcium is around 400-425 ppm, alk around 3.0 meql, don't have a test for nitrates or phosphates, but no out of control algae.