Hi I have a 20Gallon saltwater tank, and I bought LED lighting which is 6500k white light and 640nm blue lights.I just want to know is this enough for 20Gallon reef tank?
Watts per gallon applies only to fluorescent lighting. Watts is a measure of power consumption not light output and 99% of the time will not be helpful in determining if you light is good for a given coral. What LED system do you have? Is it high output? Some LED isn't going to be much usable light output at all, and other LED lights can rival metal halides on output. Also the type of reef matters on lighting. There are some corals that can thrive under little to no light (like a sun coral) and some need very intense lighting (like many acropora). Many are moderate light requirements and do well in a wide range of lighting (like many LPS such as brains).
Depending on what corals you have, you may need around 2-4 watts per gallon. So 40-80 watts should be ok. 6500 k refers to Kelvin and is a color temperature, not a brightness measure. I don't have any LED lighting on my tanks (I use T5s), but I hope this helps!
