The CRI number will give you a clue as to how accurate the colours you see are. A CRI of 100 should give you the same colour rendition as sunlight. The CRI is usually on the tube, and usually, the higher CRI numbers will be on tubes around 5000K. These 2 numbers don't tell the whole story, as some tubes have high CRI numbers, with poor light for plants. generally, tubes in the 5000 to 10000K range will grow plants decently, although they will have a range of CRIs. The actual colour spikes the tubes produce, in the proper range for plant growth, will determine how well they work. Also actual light output, tends to be much higher in tri-phospher tubes. A lot of people seem to loke the higher kelvin tubes because of the bluer light, which show off some fish. personally, I prefer a tube around 5000K., such as Philips Natural Sunshine, although their daylight deluxe is not bad either, and at 2 for $6.00, is the best deal in a T12, at HD.
