Aquatic Plant Bulbs

I have a beautiful 75 gallon tank full of heathy plants.
Plants perfer red and blue spectrums.
I keep two 48" "Triton" bulbs (a full spectrum bulb with high red 
spectrum) and two 48" "Coral Life 50/50" bulbs (high blue spectrum) on 
my tank.
Change the bulbs every six months because the phosphors burn out and the 
bulb will loose blue specrum.  And when you loose your blue spec. the 
plants no longer thrive but the algae will.