if I have two 3400k bulbs, is that the same as having one 6800k?

nope.

unlike watts, K is the color. So 2 3400k (say 15w) is equilivant to 1 (say 30w) 3400k bulb.

my .02

If you wanted plants, you'll need 5500-10000k. Anything within there will work and comes down to personal pref on which, as neither will grow plants better than another.

Yeah I just want low light so was aiming for around 7000k. Its a 20w bulb. Basically I've only got about an inch space to put the light under the lid and no room on top of the tank so brought a fixture you put in a kitchen to light up the work top, like an under cabinet one. It fits perfect but I guess ill have to hunt down a 6500k-7000k bulb for it. I really wanted a couple of T2s as there something per watt is really good and they don't waste the green and yellow in the spectrum.....but they seem to be like gold dust, can't find them anywhere!

The plants I'm growing is amazon sword, java moss and something that looks like a mini bamboo plant. There doing ok so far but I do have natural daylight on the tank for most of the day.

What size tank and do you have some room above the tank.

I really like the spiral flourescent screw in type bulbs. In round reflectors and just set them on some 1/4" sq plastic grid. For 4' tank you can use shop lights. But for smaller tanks that type of light is very effective and inexpensive.


my .02

the tank is 36" long i think. theres room above it but not all of the top is glass. i did think of over head lights but it wouldnt reach all of the tank, id have ends in shade all the time!