Yep! They come stocked with one 10K and one full actinic, which personally I think its a waste to have such limited lighting even more greatly reduced by wasting the available wattage on actinics. The jury is still out, but most agree that marine fauna to not benifit from the actinic, it just looks better to us. by switch to a 50/50 bulb, you're gaining 33% more usable light in that nano system, without having to modify it