Success with LED and SPS

[mike31154]

Originally Posted by mrhasan

UV (390nm) on the other hand, is actually bad, possibly because the wavelength gets shorter in water from the source.

Would you be so kind as to give a quick summary as to why this is so, 390nm falling in the UVA spectrum? I don't wish to watch a 20 minute video about full spectrum just to find out about the bad UV. A quick search on the UV spectrum seems to indicate that anything above 400nm isn't really UV, but simply a violet. So what's so harmful to coral @ 390nm? Thanx!