Coralife 20 000K T-12, good idea??

[pokerboi]

Hi everyone,
I want to have a thriving planted aquarium so first thing I need is a good light bulb. I have a housing for a 24" fluorescent bulb with 2 prongs at each end.

I'm thinking of buying this bulb:

Coralife 20,000K 20W T-12 Fluorescent (http://www.bigalsonline.ca/StoreCatalog/ctl3664/cp44816/si1320212/cl1/coralife_20000k_20w_t12_fluorescent_lamp__24?&query=24%22+light&queryType=0&hits=12&offset=)


I only have a 29 gallon, but I need strong light to grow plants. Would you recommend I use this bulb? Maybe 20 000K is too strong. :help2:

[Jspigs]

I would recommend a k rating of about 6700k.

[gmh]

The 20000k is too blue for good plant growing. If you only have room for one bulb I would concur, go a plant or daylight bulb, something between 6000 and 10000k.

[Slappy*McFish]

The K rating of bulbs has nothing to do with the bulbs being 'stronger' or more intense. It simply lets us know the range of the bulb's spectrum. A K rating of 4000K is reddish, 5000-6700K is commonly referred to as daylight and closely represents natural sunlight. It is a more balanced light incorporating red, blue and yellow light. Most plants do well in this K range. 10,000K is a nice bluish white and is a very popular choice with many people. Anything above that is mostly blue (including the 20,000K bulb.) It is best left for marine setups.

[pokerboi]

I always thought the higher the K rating, the better plants would grow. Clearly, I was wrong. Next time I visit big als I will probably pick up something around the 6, 700K-10,000. Thanks for the input!

[dundadundun]

hmmm... i would see if you can get a t8 bulb to work in your fixture also. you'll get a little more light out of the thinner bulb. might help.

[pokerboi]

What does the T-rating mean? thickness?

[dundadundun]

the number after the "T" represents 1/8 of an inch.

to put things into perspective this means that t2=1/4", t3=3/8" t5=5/8" t8=1" and t12=1.5" thick tubes. thinner tubes give off more light and can be reflected better with a reflector since there's less bulb in the way.

[FSM]

the 20000k bulb is probably very blue, which looks terrible on a planted tank.

6500k-10000k is slightly yellow to slightly blue, and looks a lot nicer.


As the others have said, the color temperature is not indicative of the light output. Actinic/blue bulbs produce somewhat less PAR than normal, but blue light penetrates water deeper (which is why deeper areas underwater look very blue)


Regardless of the bulb you get, a single tube probably won't be adequate. Double it up if you can.