Bulbs in the 3,500k range look pinkish/red which is great for plants but algae would take advantage of it. Bulbs in the 5,600k - 6,700k range have greenish/yellow hues which closely resemble natural sunlight. 10,000k bulbs look white and anything higher for example 12,000k -15,000k looks bluish but is not beneficial for FW plants, only good for corals. 50/50 bulbs mean half/half, one side is actinic 420/460nm and the other side is usually 10,000k. Only the 10k side would be beneficial to your plants while the actinic side would just make things look cool. Actinic is basically a black light bulb, you know, the bulbs they use to make fluorescent black light posters glow, the bulbs they use at night clubs and bowling parlors. Btw Granny, your dog must look awesome under a black light!
Remember also that manufactures use different techniques and materials when making their bulbs so X brand 10k bulbs will be a slightly different colored then Y brand 10k bulbs.
Try experimenting with different color temps to get the color you want. I use three different colored bulbs, one 3,5000 which makes the reds and oranges in my fish pop, a 5,600k and a 6,700k which make the blues and greens pop. If you use separate timers on each light you could also make a dust/dawn effect with the different colors. I'm kind of getting tired of that yellowish color myself so now I'm thinking of switching out one of the bulbs to a 10k and leaving the 3,500k. Do you still have your old fixtures? Try putting one of them back on and see how it looks with the 6,7k that came with your new fixture and the 10k you bought and see which one you like better. If you choose the one that came with the corallife fixture then you could return the 10k and get your $23 back.
You'll also have an increase in light which will increase plant growth but might stimulate algae as well.
Hope this helps,
Leo.
