High Output Florescent lights

[DavidCampen]

Originally Posted by Call_Me_Bob

really? thats odd. we use it for planted aquariums all the time, usually along side a 6700k but sometimes alone.

Color temperature has very little meaning when applied to fluorescent lights. When a manufacturer calls a lamp 10000K, all that means is that the manufacturer is trying to imply that this lamp will look bluer than another lamp that is said to be 6000K. As Connie said, a true blackbody radiator at 10,000K would be emitting mostly in the ultraviolet.

As for lumens - this is a measure of how bright a light would appear to a _person_. Human vision is most accute with green light at 550 nm and drops off very rapidly at the wavelengths that plants best utilize. If you want the most lumens per watt then get a lamp that emitts green light, it won't be very good for plants though. This is why fluorescent lamps that have the highest lumens per watt have lower Color Rendering Index (CRI) values; to increase the lumens per watt the manufacturer has to increase the proportion of green light which lowers the CRI.

In terms of supplying the most amount of fluorescent light per watt that will be useful for your plants, the color of the fluorescent bulbs is not very important. The best you can do is try to get a lamp that produces very little green light, to do that though you would have to look at the emission spectrum of the lamp not the so called Color Temperature and not many manufacturers provide emission spectra charts for their lamps.

[Call_Me_Bob]

Originally Posted by DavidCampen

Color temperature has very little meaning when applied to fluorescent lights. When a manufacturer calls a lamp 10000K, all that means is that the manufacturer is trying to imply that this lamp will look bluer than another lamp that is said to be 6000K. As Connie said, a true blackbody radiator at 10,000K would be emitting mostly in the ultraviolet.

As for lumens - this is a measure of how bright a light would appear to a _person_. Human vision is most accute with green light at 550 nm and drops off very rapidly at the wavelengths that plants best utilize. If you want the most lumens per watt then get a lamp that emitts green light, it won't be very good for plants though. This is why fluorescent lamps that have the highest lumens per watt have lower Color Rendering Index (CRI) values; to increase the lumens per watt the manufacturer has to increase the proportion of green light which lowers the CRI.

In terms of supplying the most amount of fluorescent light per watt that will be useful for your plants, the color of the fluorescent bulbs is not very important. The best you can do is try to get a lamp that produces very little green light, to do that though you would have to look at the emission spectrum of the lamp not the so called Color Temperature and not many manufacturers provide emission spectra charts for their lamps.

thanks for shedding some light on that!

[Stray59]

I understand what you are saying and it makes sense. I appreciate everyone's input, but to be honest I feel the conversation has taken some confusing tangents. I am not a "light" person in the sense that I have never studied lightwaves, emission sources, human vs. plant light perception; at least not to the incredible lengths that some of you have.
I kind of wish I had just asked for a good brand and model number but I doubt that this would have altered too much of the discourse as I am sure that every choice would have multiple opinions.
Currently I have 1-T12, 2-T8s and one T5 HO fixture. I will be adding more T5 HO, but to be honest the combo of the T12 and the T8 bulbs are working nicely as I have a Brassovola nodosa that is moving into bloom under these lights. I will post the pics when it does open.
I was able to find the light scale on that package that showed where the T12 and T8 bulbs rated and I mixed red and blue tubes. The T5 had no scale, so I will let you know how they work out.
Thanks for everything !

Steve

[Orchids4ever]

Hi stray59
i for sure know nothing about Lights... got mine at a hydrophonics Store- at there advise i bought
4' T5 -4 bulbs- 2 at 2700 K- called Sun Blaster
and 2 at 64000K- they work great for me.I mixed them up one of 64 then 27 then 64 , then 27.
If that is of any help to you.

[Stray59]

That is great info. I believe highly in mixing bulbs to get more spectrum, and it sound like you have a great combo.
Thanks
Steve

[Ray]

Originally Posted by DavidCampen

Color temperature has very little meaning when applied to fluorescent lights. When a manufacturer calls a lamp 10000K, all that means is that the manufacturer is trying to imply that this lamp will look bluer than another lamp that is said to be 6000K. As Connie said, a true blackbody radiator at 10,000K would be emitting mostly in the ultraviolet.

Once again, none of this is incorrect, but I think you may be treading a bit out of context here, David.

The "actinic" bulbs, often labeled as 10,000°K, that are intended for growing aquatic plants and especially corals, are not merely made to "look" bluer to the human eye - which is what the "corrected color temperature" is focused upon with most fluorescents. In order for there to be an appreciable amount of UV emitted, the glass used to make the tubes is higher in silica and lower in the glass modifiers than are most other bulbs. To take it beyond actinic to UV bulbs used for germicidal applications, the bulbs are pure SiO2, as it does not block the UV.

[Call_Me_Bob]

Originally Posted by Ray

Once again, none of this is incorrect, but I think you may be treading a bit out of context here, David.

The "actinic" bulbs, often labeled as 10,000°K, that are intended for growing aquatic plants and especially corals, are not merely made to "look" bluer to the human eye - which is what the "corrected color temperature" is focused upon with most fluorescents. In order for there to be an appreciable amount of UV emitted, the glass used to make the tubes is higher in silica and lower in the glass modifiers than are most other bulbs. To take it beyond actinic to UV bulbs used for germicidal applications, the bulbs are pure SiO2, as it does not block the UV.

10,000k bulbs are different than actinic bulbs. i dont know what exactly actinic are as far as kelvin, but they are to make colors in a reef tank 'POP' and are usually paired with a bulb in the rang of 6,500 to 10,000 kelvin.

[Ray]

Originally Posted by Call_Me_Bob

10,000k bulbs are different than actinic bulbs. i dont know what exactly actinic are as far as kelvin, but they are to make colors in a reef tank 'POP' and are usually paired with a bulb in the rang of 6,500 to 10,000 kelvin.

That's not what I was told when I had a marine tank, but I'll bow to your expertise!

I suppose the real point is that the 10,000°K bulbs are intended for fish tanks, not for non-aquatic plants.

I still think back to my days of under-lights growing (which ended 35 years ago), when I used 50/50 wattage-wise, cold white fluorescents (lots of blue, little red) and incandescent bulbs (just the opposite). The plants grew great.

[Paddle_grl]

I think your light choices sound pretty great. I gave up buying "grow" florescent lights a long time ago. Not really worth the money in my opinion. I have T-8's but would love some T-5's for my succulents. I found using a soft white and bright white provide the full spectrum the plants need, and are nice on the eye as I have a cabinet in my living room. I'm too cheap to invest in any more lights!