Buying Light Bulbs

[only6foot6]

I used to use some T-12 bulbs from Walmart that were $8 for a 2 pack. I thought they were the perfect bulb. They had a high lumen output and they were 6400 K rating. I had them for about 6 months and my plants did nothing. I then read on this site that the K rating does not really matter for plant growth.

What really matters is if the bulb is rated full spectrum. I then bought some full spectrum bulbs from Home Depot and my plants took off. The only problem is the full spectrum bulbs are 5000 K. A little too yellow for my personal taste but I haven't been able to find another full spectrum bulb with a higher K rating.

Loaches R Cool - What K rating do the T-8 bulbs have?

 

[loaches r cool]

The philips daylight delux at home depot are 6500K or 6700K I cant remember for sure. If you comparing them against the T12 version they are the same, they use the same phosphors and such, just that they draw a little less power and produce a little more lumens than the T12 version. About the K rating though, yeah its not as big of deal as many think. But also realize that the K rating is not verry accurate with flourescents, its not a true Kelvin Temperature, is a CCT or Correlative Color Temperature. This is because they give of light from phosphors being stimulated mostly by ultraviolet light. The Kelvin scale is based of from a 'black body radiator' basically think of it as light given off from the glow of hot metal.

only6foot6 - full spectrum, or daylight bulbs, are also not needed. Almost any plant bulb out there will NOT be full spectrum. Thats also why most dont even have a K rating. Full spectrum usually just means that there is red green and blue spectra in the bulb. Most plant lights are only blue and red and skip the green since its the least usefull for plant growth. But full spectrum is what normally gives an acceptable plant lighting plus looks good to us.

 

[Mgamer20o0]

Many have had good luck with the cheap ~$7/pair home depot philips daylight delux 32W T8. They put out more lumens (not the best measurment for plants though) than thier T12 counterpart plus the bulb is smaller and less restrike. Generally the smaller diameter bulbs are more effecient than the large ones, plus the smaller diameter bulbs have less restrike - especially if your using a good quality reflector.


only6foot6 - full spectrum, or daylight bulbs, are also not needed. Almost any plant bulb out there will NOT be full spectrum. Thats also why most dont even have a K rating. Full spectrum usually just means that there is red green and blue spectra in the bulb. Most plant lights are only blue and red and skip the green since its the least usefull for plant growth. But full spectrum is what normally gives an acceptable plant lighting plus looks good to us.

loaches r cool makes a good point. i have spent hours and hours reading different opines. i have switched to many different t12 bulbs and a couple t8 bulbs. there really isnt one great way to pick a bulb. each person is limited to what they can find around them if they dont want to buy off line. there are so many factors on light its not easy. i now use philips daylight delux 32W T8 bulbs.

in the end i think it comes down to buy the bulbs if you dont like the color in your tank take them back. if you dont think your getting the light you need try a different bulb.