What's the difference?

[lilredwuck]

I was looking at getting some new bulbs, to go with my metal halides. I have a Power Compact 65w 48". I was wondering what the difference is between the 420nm, 460nm actinic and 50/50 bulbs were. I know the spectrum is different, but is it a big deal??

 

[stanlalee]

well yes and no. they are supplemental since you have metal halides so the difference cant really be considered a big deal as far as coral health BUT all three spectrums look way different. true 420nm (I say true because many pc bulbs like coralife pc actinics are nowhere near true 420nm bulbs) are purple and under strong white halides will hardly make a difference in the look of the tank. flourescing corals will have additional pop and 420nm is the spectrum responsible for coral pigmentation growth so it more functional than blue (460nm) spectrum but the light itself is visably dim and wont change the color of your tank much. 460nm is bright blue and will add a cool visable blue tint to your tank. if you want to add some obvious blue these are the ones to get but they wont encourage color pigment growth like true 420nm. they also have more usable PAR for actual photosynthesis than 420nm (not that this matters, its still weak and you have halides for this). I really dont see why anyone would use 50/50 bulbs as supplements unless their halides were too blue and they wanted to whiten up the look a little but not so much as to use outright 10k supplements.

 

[lilredwuck]

Ok, so what do you suggest? Keep the metal halides by themselves or would supplimenting them help them vs. costs? Or do I stay with a 10k halide or buy 14 or 20k or a mixture of 2?

 

[lilredwuck]

Read this other thread just after I posted, and he answered my question! But if you are curious....

Originally Posted by SCSInet
http:///forum/post/3182892
Many people will tell you that watts-per-gallon is an obsolete term that's not used... and while it is true that some of the new technologies out there are game changes, the wpg rule is still viable when applied to halide lighting... IMO. In your tank, I would have at least 700w of light for a full reef where you could keep anything you wanted.
Normal halide lamps are not of the spectrum that you require, you need to use lamps made for reef tanks. I've never heard of "coral grow" lamps. Frankly, if I were you, I'd use my $60 per lamp to buy from a known manufacturer like Radium, Aqualine, Ushio, etc. Since you are not using supplemental actinic lamps, the 14-15K range is what I'd use.