Led Lens

[Steve H.]

I've just started looking around at DIY lighting, and I have seen most people choose 3w bulbs with 30 degree lens'.

Any good sites that I could use as a resource to help me calculate my PAR, and tell me the difference between a 30/60/120 degree lens?

I'm looking to set up a Nano reef, so it needs to be pretty intense. And, if that works out I would like to swap out for LED's on my planted tanks.

Thanks for any reply!