Call my stupid, but with the twin arc bulbs, aren't they built such that 10k turns on one time the bulb fires and the next time 20k? If that's true, do you then get a 10k look one day and a 20k look another? Maybe I'm not understanding the 10/20 bulb correctly...I love my 36" SE MH/LED Reefbrite I also use the 10k/20k Dual arc. I freaking love it. I've used AI Vegas, AI Hydras, T5 supplement,. Then Kessil AP700's. Then last it was the ATI 8 Bulb 48" dimmable with two 48" Reefbrite XHO Actinic strips,. These reefbrite pendants are cooler than my ATI T5 setup. Oh. And yes I use the reefbrite 250w digital dimmable ballasts. Picture was without a lens filter. So wayyyy to blue