MH and HPS Side by Side

[myshtern]

I plan on using 2 400watt lamps side by side. Originally I was going to do two HPS bulbs but now I'm thinking it might be better to use 1 MH bulb and 1 HPS bulb to get a fuller spectrum. What do you guys think? Will the MH bulb help at all or should I just stick to the two HPS bulbs I have now?

Also, what would happen if you put a 1000w bulb into a 400w ballast?
Would it just not light up fully?

[KingJ]

wouldnt turn on

[GigZ-16]

I think the ratio of MH to HPS is either 1 HPS to 2 MH, or 1 MH to 2 HPS. I don't remember which is the best to use.

[myshtern]

?????

[andyduckets]

if heat and power useage arent a issue, do wahtever you want. i prefer to only use one or the other for power and heat reasons. oh ya and read this guys tutorial on lighting you can pretty much skip the first 3 posts; and look at the 4th post. in that 4th post you'll see a bunch of pictures. the thirrd picture is the most important one; it shows you what color spectrums of bulbs (temp in kelvin) produce the most chloroplhyll activity.

http://forum.grasscity.com/absolute-...-lighting.html


either way u do it will be fine, as long as theres enough light for the space.

[hymee]

Why would you want to run them both eh? Just use the metal halide while you are vegging amd the HPS while you are flowering. I'm growing 12 plants with one in a small space. You don't need them both. Get a combo or hook them both up and use one and then the other respectively. Just wasting juice otherwise unless you are growing a lot.

[RichardDean]

or cut the bullshit and run Ceramic Metal Halide bulbs through the whole grow and get the best of everything in one bulb. You won't regret it.

[yah00]

Use 100w MH to 200w hps.
800w hps
400w mh.

But in vegg. just MH

[Don Piano]

HPS is fine for vegetative growth and flowering as well. Many growers will often use HPS only for veg and flower. Problem with HPS is it allows the plants to stretch. Benefit of HPS is incresed lumens per watt and lower bulb temps.

Metal Halide is pretty much only good for veg, although you "can" flower with them, it is not recommended. Problem with MH, Higher burning temps, not good for Flowering Alone, and lower lumens per watt vs HPS. Benefit of MH is compact bushy growth, and decreased distance between nodes.


SO my conclusion to this subject is.....

Using HPS along with MH during veg stage gets you incresed lumens over using 2 MH.
Using 2 HPS during veg stage will give you increased distance between nodes.
Using 2 MH would be "normal" in veg.
Using HPS along with MH in the flower stage helps to keep growth compact and bushy but you could be getting more lumens and less heat in there with a 2HPS setup.

I would use the HPS MH combo for veg but switch to 2 HPS for flower.
However I would not consider this an advanced growing technique.

[eL Tauro]

the hps to mh ratio for veg is 2 mh to 1 hps and for flowering is 2 hps to 1 mh

[mordgrow]

HPS puts out more lumens per watt.

I wouldnt even buy MH were I you.


also, note this equation 400w + 400w does NOT = 800w. its just 2 400w's from different angles.


if you can go higher wattage, do it, thats the only regret with my setup.

[RichardDean]

Light Spectrum.
The average color temperature of the sun is 5800 Kelvin throughout the year. What we see on earth has barely measurable spectrum differences between spring and fall.


The sun produces energy in pulses, like a carrier wave. Let us consider the photosynthetically active portion of this pulse, from the lowest frequency--red (675 nm)--to the highest frequency--blue (400 nm). (“nm” means “nanometer”. A lightwave that is one nanometer is one billionth of a meter in length.)


This pulse is like a train, with the blue in front and the red in the rear. The Red light acts like an engine placed at the end of the train, pushing the orange, causing a chain reaction, the whole spectrum working together synergistically. The best light for plant growth is full spectrum, like the sun, with a slight increase in red spectrum due to evolution and the fact that red travels through forest canopy better than blue.


Red light is the most efficient monochromatic spectrum for plant growth. However, all the colors have functions. If a person were especially good at hearing bass sound, that means the other pitches should be emphasized, so that one could hear the whole melody. For light to be efficient for plant growth, it must be full spectrum with close to equal linearity and amplitude through the production of 400-700 nm, with a slight bump in the red.


The blue spectrum has the highest energy and shortest wavelength [see: Light Measurement Handbook (1997), by Alex Ryer, page 8].




Blue is in the front of the light train, acting like a spearhead to penetrate the leaf, carrying the other colors with it. The far blue range includes UV-B, similar to what is found at high altitudes, and increases the prized phenolic compounds. This increases the flavor of peppermint, licorice, pepper, etc.
Conventional wisdom dictates that the growth phase be illuminated by a quartz metal halide (for blue light), the bloom phase by a high pressure sodium (for yellow/
orange light). However, a full spectrum is needed for all phases for a variety of functions. Blue induces growth hormones and rooting, and reduces stem elongation. Red induces flowering hormones, and provides energy for growth of flowers and leaves. Using only quartz halide during growth phase results in slow growth due to less red light. Using only HPS light during flowering stage often causes leaf yellowing, due to lack of growth hormones; and tends to cause stem elongation.


An artificial light which reproduces a red-enhanced full spectrum is the “Ceramic Metal Halide” or “High Pressure Metal Halide”. This has more blue than a metal halide with a conventional quartz arc tube, and more red than an HPS, so it’s spectrum is optimum for all stages. The Ceramic Metal Halide (CMH) features a ceramic arc tube like an HPS, and uses an HPS magnetic ballast. Philips has recently come out with a horizontal version of this bulb, resulting in longer bulb life and 1000 lumens more compared to a vertical cmh bulb operating horizontally. Generally, horizontal works best.


For those limited to magnetic ballasts, CMH is probably the best plant light available. For the Life Light electronic ballast, Life Lights also produces full-spectrum pulse-start metal halide bulbs. These are more efficient than normal halides, with better spectrum. They are designed to accommodate the 100,000 pulse rate of the Life Light electronic ballast. These come in four spectrums:
*6K for rooting and early veg
*4K for general growth/bloom
*3K for late bloom
*10K for finishing (last 2 weeks)
If you can’t afford all four bulbs, the 4K is fine for all stages.


The CMH has a better spectrum and is more efficient electrically than the retro-fit HPS that operates on a MH ballast. The retro-HPS is more expensive, lasts only half as long, and has reduced output, compared to a regular HPS.


Also the reason a HPS and MH together would be better the light train is crucial. Hope that info helps. In Hindsight I should have posted this earlier for all those gentlemen I was having a debate with in the thread we had running in general indoor growing. Mixed spectrum period is the only way to really get even close to emulating the sun's capabilities in a indoor environment.