lyndatu

Hello

I'm planning to start an aquarium garden to grow little seedlings and propagate them to save some money from buying older plants. But I was wondering - what light color is best for plant growth and health? I currently have a pink light in my 20-gallon tank with quite a low wattage and I have an Anacharis(medium-light plant) plant in the tank and seems to be doing fine and healthy for a month, although its foliage is quite thinner. What light color do you think is the best for plants?

Thanks in advance!

GreenMan13

5500K. This is basically day light so it is white. Most fresh water plants are in shallow water so this is what they get naturally. Plants need a little of ever color range to grow to the most potential.

lalynya

Oh I know this answer...we did an experiment in bio lab last semester where we actually measured the waves of light in the chlorophyll...so anyway..green will not do a dang thing for the plants pretty much....becuase white light is actually all the various colors of the rainbow even though it appears "white"..(R.O.Y.G.B.I.V)..It will be the most benificial for your plants since various plants do better with different spectrums..it all has to do with which color the plants use to create the energy it needs to sustain life...ummm ok I'm done now.

Jim

close, but not quite. The magic number you want is a 6700K plant light. But those tends to be a bit pink, so most people mix them with 10,000K full spectrums to balance them out. This is what my tank has. Actually mine has 2-65Watt 6700K T-5 High output dual-tubes, 2-21Watt 6700K T-5 plant tubes, and 2-21Watt 10,000K full spectrum tubes. These are what I'm using currently on this tank, my 46 gallon Swamp:



The hard part is for plants you'll need some serious wattage, I'd recommennd at least 2 watts per gallon or better for your plants to thrive. Also, have you addressed your substrate? 99% of all plants will die in just gravel.

GreenMan13

Sorry, I didn't mean to state specifically 5500K but in the 5500 ballpark. You do want something full spectrom but as long as it looks even slightly white that means it is full spectrom. Color temps in the 5500K to 6500K will be ideal enough for you unless you really want to get into researching plants and lights specifically.

Just looking at the color temp of a bulb does not give you much on how much of each color there is actually. Going from one brand to another a 5500K bulb can be the same as a 6500K bulb since there is no defined way to measure color temp accurately since it is based off black body radiation. To visually see where color temps are to each other look at this chart: Color Temp. Color temp is not a linear line in terms of color spectrom. As this chart shows there is a line showing color temperature as a curved line but depending on what the spectrom of the bulb is exactly, it can be anywhere on that plot. What you want is a full spectrom light source though which is white. Looking at the chart you can see that is basically 5000K to 10000K range. All I'm trying to say is if you really want the best light for a plant, you will need to determine how much of each wavelength that plant needs and find a bulb that offers that color spectrom. Other wise just go with a bulb that is close to the color spectrom or color temp of the sun: Color of the Sun The color temp of the sun changes through the day in the range of 5000K to 6500K bty.

Jim

Oh, I understand what your saying, and I didn't mean to sound like I'm arguing. What I meant is if you go to the store looking for aquarium plant lights you'll find them labeled 6700K plant-bulb. That's how they're sold, and what most books recommend. I don't know how they came up with 6700 as the ideal number, I'm just repeating what I've read.
Now, as far as your point I've been experimenting with different CFL's and I agree, I think a 5000K would probably work.

GreenMan13

Sorry about that last post too. I was in kinda a grouchy mood too so thats why I might have sounded a little angry also. And its sometime hard to tell the tone of text. It's all good though now.

Jim

Oh yeah, we're all good. I just didn't want you to think I was being a know-it-all... yeah right! The more I learn the dumber I feel! hehehe