Hi Liz, Since I have been growing for over 25 years I have found that the 4' fixture is best for my plants and also the most economical. When I was working and could afford them I used Varilux bulbs which I found gave the plants a great growth rate, however, they are expensive and cost retail over 12 dollars each. Since retiring I switched to 40 watt cool whites which I purchase by the box at Home Depot or Lowes. They work well and give me no problems. I have on occassion in the past used Gro-Lux and Gro-Lux WS. Both bulbs give good growth to the plants and make the plants look really beautiful and healthy under the light. But when you remove the plant from the light into natural light there is great disappointment. They loose their color and look rather ordinary. The Gro-Lux WS bulbs were always cheaper than the Gro-Lux. Many people prefer to use one cool whit and one warm white to grow. Since I cannot find warm whites I now use cool whites exclusively. Hope this helps. Fred in NJ

If you are looking for a LED light and you want something that approximates a 400 or 600 watt HPS, you aren't gonna find a real system for less that the Procyon. Anything that you will find of the variety of the cheap led panels or the ufos have pretty much been shown to be useless cause their leds are too weak as any hydro store owner will tell you. The state of the technology is such that there are really only two products out there that really work -- procyon 100 or the ti-smartlamp 600 and its stronger 1000 watt version the Smartbar. If you take a look at greenpinelane.com you can see tests on all of them. The thing to remember about leds is that while they cost much more than HPS initially they payback the difference quite quickly, in 1 to 3 years depending on how much you pay for power and whether you need to cool, which you will have to do if you use HPS. They have a lifespan of about 10 years so the cost savings overall of LED versus HPS can be quite important, usually somewhere between 40% to 100% when you factor in the power savings. I switched to the Smartlamp myself for the powersavings once I was sure it could flower which it can since it is the only LED out there that i know of that has more than just red and blue leds. Good luck in your choice.

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The GroLux bulbs, from what I can find, are generally much lower in lumens than typical fluorescent bulbs. This does not reflect a lack of suitability for growing plants, but rather that lumens are not a useful measure for how "good" an artificial light source is for growing plants. That's what PAR is for. Lumens measure how bright a light appears to the human eye (which prioritizes yellow and green wavelengths), while PAR measures how much of the light produced can drive photosynthesis (which prioritizes blues and reds). Since GroLux bulbs are heavy on blues and reds at the expense of yellows and greens, they produce half the lumens of a normal fluorescent bulb - but are likely to be a bit better for photosynthesis (I'm guessing.. you'd have to find PAR values to actually compare the two).