Nope no problems with mixing bulbs. They come in alot of colors (kelvin temp) the bottom of the spectrum say 4000k would be quite yellow 6500k would get more white 10,000k would be whitish blue and 20,000k would be more bluish white. Then of course you have Actinic (blue) which makes anything with blue look great. I use a mix of 10k and actinic on my cichlid tank, I really like that combo, but what's pleasing to my eye my not be to yours. Just play around with some differant combos till you find one you like. Also you might look at doing just a twin strip if your not getting into plants at 2wpg without anything competing for nutrients you could have algae issues.