It's strange though how two manufacturers claim their bulbs peak at 420 nm but they can be totally different color. Makes it really difficult to know who is telling the truth
No, it is actually quite easy. It is no problem for two bulbs to peak at 420 and then for bulb "a" to have a higher peak at 470nm mark than bulb 'b" . Bulb a will still have that peak at 420 but it will not be as blue as b. Thing mixing paints. 420+420 / 2=420 bluer..........420 + 470/2 = 445 less blue. Bulb b will also have a higher K than a. One always need to look at the SED Curve of a light bulb so you know what is going on, such as the one I posted on the other reply. See that peak at 550 & 580, now pretend they are not there. Still a peak at 420. Now pretend that peak of 450 is not there. 420 is still there and as we remove these other peaks the bulb becomes more actinic and has a higher K temp
Here is an true actinic, what corallife claims theirs is
Hellolights
No SED but also claim to be a true actinic .So I can't say which one is more actinic but it appears the Hello is, based on observed color.
Nowadays, "Actinic 03" has become the marketing term used to identify "blue" looking bulbs. Many bulbs are passed off as "actinic", when they are just a blue bulb. Blue 7,100K bulbs are visually brighter than HelloLights Actinic bulbs. Blue bulbs will NOT fluoresce your animals as well as our Actinic bulbs. Many others sell "actinic", but they are really selling blue bulbs.