View Full Version : Conversion bulbs vs. separate ballasts?

01-16-2007, 02:05 PM
I'm tying to sort out what [electronic] ballasts I should be considering.
Seems 600 HPS has an edge from efficiency standpoint, but needs MH conversion bulb.
From what I can tell, roughly, conversion bulbs seem to be about 20% more expensive that regular MH.
I'm leaning toward two 400 Watt ballasts that can use either standard HPS or standard MH. Even though this is more expensive (and maybe a little less efficient -- comparing 400 watt to 600 watt ballasts/lights).
This way I can use both as MH during growth stage and both as HPS during flowering stage (or maybe combination for experimentation).
The 600 HPS Sylvania Growlux looks pretty good. Should I consider 400 running both a 400 MH and a 600 HPS?
I just feel that whatever I do, I'm better off spending the $$ upfront on the correct ballasts instead of being stuck with having to use more expensive (and less choice) MH conversion bulbs.
Any suggestions?

Life Light
01-17-2007, 12:10 AM

First, a bit about electronic ballasts you should know. An electronic ballast takes 60 HZ, and ramps it up over circuit boards to make it into 30,000 to 130,000 HZ. Only buy a digital ballast, and one that operates over 100,000 HZ, because you arent FCC compliant at less than that, and it causes problems.

Electronic ballasts that operate at 30,000 HZ are sending all that juice over a lamp that was made for 60HZ. You can operate a Pulse Start Metal Halide, thats designed to withstand the 4KHZ pulse that those electronics put off. Electronics will fry a regular metal halide lamp. HPS lamps will ignite, but will burn out under the extra HZ over time.

Plants want full spectrum light, period. PAR light is visible light, so give them the spectrum all the time. HPS light is terrible for plants. If the Sun had been HPS light, life wouldn't have evolved beyond slug form.

I'd recommend you check with your local hydroponic dealer to weigh out your options on lighting. There's high end gear, and low end gear. The shop owners can guide you through the maze of choices. Let me know if you have any other questions.

Hope this helps.

01-17-2007, 12:10 PM
I'm not following the difference frequency plays in lamp life. Voltage I can see, but in lighting circuits, I've never seen the frequency of the AC current to be a factor. In fact doesn't higher frequency (in most instances) result in more efficient power transfer?

If HPS are "no good", why are they so widely used as plant grow lights? I received one recommendation that if I were to use only one light, it should be HPS instead of Metal Halide. From the spectrum charts, it appears to me that the "unenhanced" MH lights are as far into the blue spectrum as HPS is in the red. Will plants, such as tomatos, produce fruit as will under MH? One suggestion was to switch to HPS at the beginning of the fruiting stage or, as the best alternative, to add HPS to MH at that time.

Life Light
01-17-2007, 09:30 PM
Frequency relates to the power and amplitude of light, not the lamp life. The lamp life becomes a factor when you use 30,000 plus HZ on a 60 HZ lamp. Too much juice for the lamp.

The reason everyone uses HPS light in this industry is because of a NASA study decades ago, that said plants are efficient at using red light, AKA, the plant efficiency curve. Well, they misinterpreted the data. It' s true, plants are more efficient at using red light, because the Sun gives them the least amount of it in nature. Red light has the fewest electron volts per photon of all the colors of the spectrum. If I shine red light on a solar panel, nothing will happen. Red light has very little energy. If I shine violet light on a solar panel, it'll make light, because violet light has almost twice the energy. WE DON'T NEED TO BOMBARD PLANTS WITH MORE OF THE RED LIGHT THAT THEYRE ALREADY EFFICIENT AT USING.

Plants, like all living things on Earth, want the light like the Sun, The visible spectrum. PAR light is visible light.

The new ceramic technology they use for lighting now, is the best of both spectrums, a high pressure metal halide. Try to use a full spectrum light, but don't use a reflector, you'll just destroy the light for the plants.