Things to watch for when changing lighting?

[Son Of Skyline]

Originally Posted by reef_raf

Sorry, the 400w radium on the HQI ballast had about 500 PAR, based on my system. Steve can confirm, but it may be lower. A Iwasaki on a HQI ballast reads 969 PAR, almost double a 400w Radium on comparable ballast. Even on the std. PFO, it measures over 700 PAR, still way above a HQI driven Radium. That radium was also 2 weeks old at time of testing. After a couple of months, the PAR was likely closer to 300.

Brad, are these numbers comparing the 250w Iwasaki vs the 400w Radium, or the 400w Iwasaki vs the 400w Radium?