1) Does it have to be from HTG Supply?

2) The 2-ft., 2-bulb fixtures shouldn't cost more than $100. But that seems about right for a 2-ft., 4-bulb fixture. Check it out - http://www.yardlover.com/sun-blaze-t5-high-output-fluorescent-light-fixture - you can find coupon codes for this site on the web, which will bring the price down. There are many other T5 lights on yardlover.com, so be sure to browse.

3) I have a 4-ft. fixture now and I'm realizing now that I need at least another one of these units (maybe even another 4-bulb fixture) to have adequate results for my plants which are in a 2x4' area with the light 6 inches from the plant tops. You may want to consider buying a 4-ft. fixture or an HPS/MH unit. Keep in mind that a 2-ft. fixture may be able to rear many seedlings, but probably only 1 mature plant. When that plant is mature, you limit the use of the light to that plant, since it must be within 4-8 inches from the light source. This leaves your seedlings too far from the light source.

Best Wishes,

Rob

I'm sure any of those would work fine. The key is to get the right bulbs. You want to buy both red and blue bulbs to get a full spectrum.

You want to buy both red and blue bulbs to get a full spectrum.

All of the commonly available bulbs (including daylight, cool white, and warm white) have a full spectrum in the sense that they provide both the red and blue light necessary for plant growth. There is no need to mix them, although it won't hurt either.

Mixing red/blue fluorescents is actually recommended by professional indoor gardeners and several websites that sell these lights.

I personally think an even mix is best, but some say more red is better. For example, an 8 bulb unit with 2 blue and 6 red bulbs. Though I haven't tested a side-by-side with 4 blue and 4 red fluorescents to refute this theory. I would think that an even mix of fluorescents with incandescent or red CFL supplementation upon flowering would be best.

Thanks for the responses everyone. You all have been helpful. I didn't even know about the Yard Lover site.

In the end, though, I decided to go with the SylverStar 2feet fixture because of its individual reflectors which I guess makes it run cooler and more efficiently. I also chose mixed bloom/grow (red/blue) bulbs.

I might get an HID system in the future.

Thanks again.

Mixing red/blue fluorescents is actually recommended by professional indoor gardeners and several websites that sell these lights.

Professional indoor gardeners and vendors provide incorrect information all the time. I've seen it far too often to let them sway me.

In the end, though, I decided to go with the SylverStar 2feet fixture because of its individual reflectors which I guess makes it run cooler and more efficiently.

Good to hear. Individual reflectors deliver a much higher percentage of light to the target area than one big reflector.

If the "red" and "blue" lights you are mixing are flourescent lamps, then consider this: They both use the same phosphors to emit the exact same red and blue wavelengths, but in different(or inverse) proportions. This is analogous to blending a 15-10-5 fertilizer with a 5-10-15 fertilizer - you end up with 10-10-10, which you may as well have bought to begin with.

To prove this to myself, I took spreadsheet data I once had years ago, published by Sylvania, which divided and quantized the emissions of about 40 fluorescent lamps into narrow spectral ranges. In several columns I combined and averaged the red and blue output of "warm-white" lamp types and "daylight" lamp types. Their average output was the same as a "cool-white" lamp. Not any redder, not any bluer.

This information would NOT apply to mixing MH and HPS lamps, but as far as fluorescent lamps go - mixing them produces no difference. You can just use medium color temperature lamps to the same effect.

Zink

@Zink: Anyone who has been on this site long enough has read Al recommendation for using a fertilizer in the ratio 3-1-2 for container plants. If your analogous assumption is correct, then a 1-2-3 fertilizer would be one and the same; though we know this is not the case.

Yes, for 6500k blue and 3000k red spectrum bulbs, spectral analysis shows the peaks (in different ratios) in roughly the same areas. But what you are not taking into consideration is the width of those peaks, which is directly proportionate to their intensity of coverage. What's more is that most people neglect to measure the strength of those peaks relative to average microwatts per nanometers per lumen. In the end, 2 6500k and 2 3000k HO-T5 bulbs provide better results than simply using 4 6500k bulbs. Try overlapping both spectral charts for each bulb (assuming the vertical microwatt figures are comparable for each bulb) to see what you're missing out on without mixing for full spectrum.

Anyone who has been on this site long enough has read Al recommendation for using a fertilizer in the ratio 3-1-2 for container plants. If your analogous assumption is correct, then a 1-2-3 fertilizer would be one and the same; though we know this is not the case.

That's not what he's saying at all. Reread his post. I think he stated it quite well.

Yes, for 6500k blue and 3000k red spectrum bulbs, spectral analysis shows the peaks (in different ratios) in roughly the same areas. But what you are not taking into consideration is the width of those peaks, which is directly proportionate to their intensity of coverage. What's more is that most people neglect to measure the strength of those peaks relative to average microwatts per nanometers per lumen. In the end, 2 6500k and 2 3000k HO-T5 bulbs provide better results than simply using 4 6500k bulbs. Try overlapping both spectral charts for each bulb (assuming the vertical microwatt figures are comparable for each bulb) to see what you're missing out on without mixing for full spectrum.

Phosphors emit light over a specific range of wavelengths. Increasing the concentration of a phosphor will increase the intensity within that range, but there is no logical reason for it to increase the range. I suspect what you are seeing is compression of the lesser amplitudes due to the tall spikes on these charts.

Also, no one is saying that everyone should use 6500K bulbs. We're saying that there is no advantage to mixing bulbs with identical phosphors when you can pick an in between bulb like a cool white or 5000K.

After thinking about it some more, it sounds like you are talking about the widths of the peaks themselves, not the total width of the phosphor emission range. And you are right about the width of the peak being proportional to the intensity. But what you are not taking into consideration is that it is canceled out by the weaker peak of the other bulb. For example, mixing a 3000K bulb with a 6500K bulb will result in a strong red peak and a weaker red peak. While using two 5000K bulbs will result in two moderate red peaks. They average out to be the same.

@penfold2:

Look here:

6500k - http://genet.gelighting.com/LightProducts/Dispatcher?REQUEST=COMMERCIALSPECPAGE&PRODUCTCODE=46763&BreadCrumbValues=CATG,_Lamps_Linear

3000k - http://genet.gelighting.com/LightProducts/Dispatcher?REQUEST=COMMERCIALSPECPAGE&PRODUCTCODE=46759&BreadCrumbValues=CATG,_Lamps_Linear

4100k - http://genet.gelighting.com/LightProducts/Dispatcher?REQUEST=COMMERCIALSPECPAGE&PRODUCTCODE=46761&BreadCrumbValues=CATG,_Lamps_Linear Fluorescent_Straight Linear_T5&SearchFieldCode=null

These spectral charts analyze 3000k and 6500k bulbs. The "Radiant Power" of the 3000k bulb peaks at about 105, 240 and 202 compared to the 6500k bulbs at 500, 490 and 310. By overlapping the two you're getting a broader spectrum than simply by using one type alone, or by using all bulbs at 4100k, which peak at 220, 610 and 400 on the vertical gauge. Even so, I have said in the past that the triple vertical spikes apparant in all of these analyses is not the only thing to take into account when doing a comparison. The dips and spikes and thickness of the wavelength between these peaks as well the radiant power of each must also be taken into consideration.

Give it up with the mixed bulb syndrome yucatan. I used to use a mix but now use 5000k and can tell no difference. Manufacturers will say anything for a sale and false advertising is now common practice.

BTW zink has been here much longer than you and has posted some REAL information and you fertilizer example is ludicrous.

I see nothing in those charts to indicate that an average of the 3000K and 6500K outputs would be significantly different from the 4100K output. And there's no logical reason for it. Phosphors have specific spectral distributions. You can alter the relative intensity of each phosphor, but that's it. What you're suggesting simply isn't possible.

@taz: First line of business: You're a horse's ass. Second, manufacturer's don't make various bulbs in different spectrums and sell them at the "same price" for profit. Just listen to yourself; that's such a ludicrous assumption. Third, zink was the one who brought up the fertilizer comparison - I simply restated his thought. Lastly, do you think that seniority as a random forum poster on a plant website has any credibility? It's all personal opinion. Does zink have some advanced degree I am unaware of? Or maybe you just have some die hard appreciation for zink? Again, just listen to yourself. Your attitude is overwhelming and you need to step back and check yourself before you get a punch in the face some day. Though, you probably don't make that mistake in real life or you'd be in a hospital by now.

@penfold2: I can't help you further if you can't read a simple chart.

People here have been trying to help you. We've explained how phosphors work. Zink described the quantized emission data that he averaged. And still you cling to some chart anomalies that, apparently, only you can see. And now you're making personal attacks on people.

I think you need to take a step back and look at some of the information that's been presented to you. There is no evidence or explanation for your claims.

@penfold2: My reply to taz was justified since he mocked me here as well as other posts. I was simply asking questions or providing my opinion and there was no need for responding the way he did so I dished it back.

I know how phosphors work; you don't need to describe that and that wasn't my concern. If you cannot read the chart that I provided then look at the wavelength chart here:

http://www.cambridgeincolour.com/tutorials/white-balance.htm

By using all 5000k bulbs instead of a mix of 3000k and 6500k bulbs, you're missing out on much of the intensity at the ends of the red and blue spectrum. 5000 K produces roughly neutral light, which is highest at in intensity at 550 nm.

That chart proves my point exactly. Pick any point on the graph, look halfway between the 3000K and 9000K lines, and you'll be very close to the 5000K line. This is what zink was talking about with his analogy. Combining a 1-2-3 ratio with a 3-2-1 ratio yields a 2-2-2 ratio. The highs and lows cancel each other out, so you get an average of the two.

"I simply restated his thought"
You twisted his thought. How becoming!

"It's all personal opinion"
But you ask for Scientific evidence?

"Your attitude is overwhelming and you need to step back and check yourself before you get a punch in the face some day."
Are you threatening me with violence? I'll send you my address! I only check myself for ticks and skin cancer.

It's unbelievable how thick you are penfold. The chart displays a 5000k line for one. Also, I never said that it wouldn't fall in between these two. I said that by using all 5000k bulbs, it isn't the same as using an even mix of 6500k and 3000k bulbs because you will not receive the same intensity at the ends of the spectrum than if you used 5000k bulbs alone. Yes, daylight and red bulbs balance somewhere in the middle toward white light, but you're still missing the point. You're missing the advantageousness of having higher radiant power by not mixing the 6500k and 3000k bulbs since their peaks at the blue and red ends are far greater than those at 5000k. Higher peaks in the appropriate areas means more useable light for the plant which yields better growth. It's not as simple as mixing red crayon with blue crayon to make purple on a piece of paper. And no amount of evidence will convince you if your mindset is this simplistic.

@taz: Just give it up man. Learn how to read too. I didn't make the initial comparison, give personal opinions without evidence or threaten you. Your "opinions" are no longer required for future reference.

It's unbelievable how thick you are penfold.

I hope you soon see the irony of this statement. Apparently you don't understand the concept of averaging. To keep things simple, let's say a 3000K bulb provides 3 units of red light, a 5000K bulb provides 2 units of red light, and a 6500K bulb provides 1 unit of red light. When you combine the 3000K and 6500K bulbs, you get 4 (3+1) units of red light. When you use two 5000K bulbs, you also get 4 (2+2) units of red light. It doesn't matter if the 3000K bulb has a higher red peak because it gets canceled out by the reduced red peak of the 6500K bulb. And the same goes for the blue end of the spectrum.

We've come to the point where we are simply repeating ourselves.

One last time:

It's not as simple as averaging. There's much more to account for when it comes to mixing red and blue light.

What you are claiming simply isn't true: That two 5000k bulbs have no disadvantages yet all the advantages of using one bulb at 6500k and one at 3000k.

It's not as simple as averaging.

It's exactly that simple. Spectral distributions can be quantized and averaged just like any other waveform. If you choose to believe that specific bulbs have some magical property that defies this basic science, then so be it.

He will never see the light.

"It's not as simple as mixing red crayon with blue crayon to make purple on a piece of paper"

If the peaks are much higher in red/blue than green/yellow it is that simple. P&A bulbs that lack green/yellow are PURPLE.