So my lfs was having a big sale on everything in store i needed to get a new bulb for my tank and all they had was a 20k bulb which is really blue. I love the look but will it effect the growth and health of my coral?
It depends on what your present lighting setup is, and the age of your present lamps, among other factors.
They'll probably be okay if you just cold-swap, but anything's possible.
