Which bulbs to buy?

[minireef guy]

I need to replace my bulbs soon and need to know which to buy. Now I have a 10K bulb and a 7100k bulb, both 55 watt PC's. Should I stay with these or go with another combo? Other choices are 6700k and 8800k.
Also, how do you know the color? The 6700k is described as crisp white, as is the 10k. The 7100k is actinic. How does this work?

 

[flydan]

Hey,
First of all let me get the disclaimer out of the way.... I am no lighting expert!
OK, the actinic is good because it emits light in the blue range and I believe that blue light penetrates deeper into your tank. Anyway, you want the actinic AND a good broad spectrim light. Most experienced reefers supplement their VHO or MH lighting with an actinic bulb of some sort.
Hopefully someone else will jump in and explain this better for you.
Dan'l