After doing a little research I've come to believe that all "actinic" bulbs are basically just blue bulbs. Depending on the brand, you get different color blue to purple. I say this because the last place I found that actually described what "actinic" is, says its refers to a wavelength thats not visible to the human eye, and is closer to being electromagnetic than actual light. I think the actinics that give the colors we like are actually just close in visible spectrum to a black light bulb. No Phosphour I know of is capable of producing EM waves. As such, finding one that gives the look you want is more important than anything else. The worst one I've ever see was so hideously baby blue it made the entire tank look like puree'd smurf.
A couple quotes from a meteorology site that deals with light spectrums.
actinic—Pertaining to electromagnetic radiation capable of initiating photochemical reactions, as in photography or the fading of pigments.
Because of the particularly strong action of ultraviolet radiation on photochemical processes, the term has come to be almost synonymous with ultraviolet, as in actinic rays.
electromagnetic radiation—Energy propagated in the form of an advancing electric and magnetic field disturbance.
The term radiation, alone, is commonly used for this type of energy, although it actually has a broader meaning. In the classical wave theory of light (or electromagnetic theory) the propagation is thought of as a continuous wavelike disturbance of the electric and magnetic fields, which oscillate in planes orthogonal to each other and to the direction of propagation. The quantum theory of electromagnetic radiation adds the perspective that these disturbances also have particle-like attributes, being quantized into photons of minimum energy that have finite momentum. The observable properties and physical effects of various portions of the electromagnetic spectrum are of considerable importance in meteorology and are discussed under their respective names.
