Success with LED and SPS

[mrhasan]

Originally Posted by mike31154

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!

Sure I will try my best to explain it

So here's the photosynthesis wavelength figure:



The main purpose of full spectrum is to hit the spikes in the graph. So as you can see, the two spikes occurs at 410nm and 428nm.

Now from sun, 390nm hits the water but since ocean have much more depth and much more volume of water, 390nm doesn't actually get in water since the wavelength increases when UV gets into water. Possibly the corals get something 410nm to 428nm (will have to do calculations but I don't know the formulas; forgot optics a long time ago :P) On the other hand, our tank is not that deep, its more clear and so on. Hence using actual UV a.k.a 390nm would actually give more or less that wavelength to the corals and according to claims (I am not sure though), they can be damaging to the coral. Hence, for example, LGB suggests using 405nm which, I am guessing, will get inside out tank at that wavelengths. Anything above 400nm will look purple but will also be very dim since our eyes cannot catch those wavelengths properly.

That's my understanding. I am not saying is 100% right since its more like learning from others and compiling my own logic to support them.