The higher the Kelvin rating of the bulb the more blue vs red the light will be. Red is relatively low K and blue is relatively high K. That's why bulbs for salt water tanks are high K and blue.

An easy and interesting experiment someone could try is two identical tanks, one with a half actinic bulb and one with 6500-10,000K bulb, and see what the differences are in plant growth in the two tanks. If the often repeated statement that actinic light does no good for the plants is true, then high light plant species will do much better in the tank without the actinic bulb.