Is having a separate MH system worth it??

so i plan on getting a hps system (not sure which wattage though) and ive ben debating wether or not its worth the extra space and money to get a metal halide system for vegetation. the only thing i know about it is that it has a better color spectrum for vegetative growth. but im just curious as to what exactly are the benefits of having the proper spectrum



also what does the ballast do??? sorry ive only worked with CFL's in the past so this will be my first HID setup

Pumert said:

so i plan on getting a hps system (not sure which wattage though) and ive ben debating wether or not its worth the extra space and money to get a metal halide system for vegetation. the only thing i know about it is that it has a better color spectrum for vegetative growth. but im just curious as to what exactly are the benefits of having the proper spectrum



also what does the ballast do??? sorry ive only worked with CFL's in the past so this will be my first HID setup

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Theres plenty of debate over this, but most people agree mh is better for vegging and hps for flowering, with hps bein the best overall. ive only worked with mh and the buds did seem a lil airy but i am still a noob. I guess in rality it depends on if you really want it or not

I would say yes if u can only get one I'd say a mh unless ur growing to sale. Hps is most efficient and "better" for flower in the sense u get a better swell. But my opinion of better comes from mh. A mh will tend to make for less bud however it tends to be more potent from the extra uv a mh puts off. Its up to you but I would rather have a short bushy tight noded plant that yiels supreme then getting 10% more at the cost of a little potency but as said before. The debate will go on til the end of time. I personally never have and never plan to use an hps. Accept maybe as supplement lighting

but what effects does a MH have on a plant if its just used for vegetative growth??

Thicker foliage as well as shorter plants with tighter node spacing. Its more suited to the plants veg needs

if thats true then im sold on a MH

i think one of each is better then 2 of one single one

Pumert said:

if thats true then im sold on a MH

i think one of each is better then 2 of one single one

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you can buy a hps ballest and put a hm bulb in it but the mh bulb wont last as long as it normaly would do ... u cant put hps bulb in hm ballest tho... hps is the way to go ... or you can buy a dual spectrum bulb that is both mh and hps in one bulb.. its a bit more but its both ...

Look into ceramic metal halide. Provides the entire spectrum!


Either way, in most circumstances it's not worth the investment to buy MH bulbs unless you're someone who has a dedicated veg chamber with a bunch of big plants.

if you're experienced with cfl's, why change your veg method? - see many examples here of vegging with cfl's that easily match other light sources
not talking flower, and i haven't used MH for veg, but i don't see that it really does much more for veg, and it's an extra cost

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Brick Top said:

Metal Halide bulbs put out a bluer light spectrum that is most needed for plants during their vegetative growth stage. Using one will give you tighter nodal spacing (less stretch than will be seen using an HPS bulb alone) and thick lush growth.
　
High Pressure Sodium bulbs put out more light in the red spectrum range, that that is most needed by plants while in the flowering growth stage, but if used for vegetative growth will cause wider nodal spacing and growth that is not as thick and as lush as a MH bulb would give.
　
What can be best is a combination of both light spectrums. Some wattage HID lights can use a dual-arc bulb that puts off both a MH and a HPS light spectrum from one bulb at the same time. An example is a 100-watt dual-arc bulb is a 500-watt MH and a 500-watt HPS in one bulb.
　
They are not available in every wattage though. I have seen them in 1000-watt, 600-watt and 400-watt but lately for some reason I cannot find the 400-watt bulb offered so I do not know if there was some design problem and it is no longer offered or if the sites I had found it on in the past just no longer offer it possibly due to lack of sales.
　
If you can use one, it would be a wise option to take. If someone is burning lower wattage HID lights and can deal with a slight increase in temperature adding a second light of the different light spectrum is a good option to take.
　
If someone uses a different style of reflective hood depending on its size and design a second bulb of a different light spectrum can be added. Some reflective hoods are designed to accept a second bulb though most are not.
　
If someone uses CFL’s it is just a matter of purchasing ones with different Kelvin temperature/color ratings and then spreading them out so their plants receive as equal of an amount of each light spectrum as possible.

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Hidden Agenda said:

Look into ceramic metal halide. Provides the entire spectrum!


Either way, in most circumstances it's not worth the investment to buy MH bulbs unless you're someone who has a dedicated veg chamber with a bunch of big plants.

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Myself I have never seen a ceramic metal halide bulb that was more than 150-watts. If they make then in higher wattage then for HID growers that do not use a very low wattage lights they could be an answer.
　
If not for those that use decent to serious wattage and want the dual spectrums of light the dual-arc bulbs or a combined lighting system is what is needed.

I do not agree with what you said about if someone does not have a dedicated vegetative grow room just for vegetative growth it not being worth using a metal halide bulb.
　
MH conversion bulbs can easily be found for most HID wattage light systems and will run off an HPS ballast.

For example someone with only a 250-watt HPS light can purchase a MH conversion bulb for around $34.00 (plus S&H if ordered online).

The benefits of the blue light spectrum over a red light spectrum during the vegetative growth stage is far more than worth the low cost and the extremely little effort of changing bulbs when you switch from vegging to flowering.

For any even half-serious grower an extremely important part of growing is the amount of grams produced per wattage used.

When you provide plants with an inadequate light spectrum at any period in their growth production will drop but your use of wattage will remain the same.

That equates to fewer grams produced per watts used.
　
Does intentionally choosing that option over one that would maximize the number of grams produced to watts used really sound all that intelligent to anyone here?
　
It sure does not sound all that intelligent to me.

growone said:

if you're experienced with cfl's, why change your veg method? - see many examples here of vegging with cfl's that easily match other light sources

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If someone uses CFL’s for vegetative growth and they do it right I will admit CFL’s will work well. The problem is that most do not do it right.
　
Few if any are willing to or can afford to pay the price for actual true CFL grow lights. Instead they pick home lighting CFL’s in different light spectrum ranges and while they believe they have enough lighting and are impressed enough by their results that they believe they did things as well as could be done and what equaled the results that would be achieved using HID lighting.
　
The chart below compares a 400-watt HPS to other forms of lighting so it is not a 100% valid example since the question is about MH but it does show how much wattage of differing types of lighting is needed to equal one 400-watt HID light.
　
They do not bother to compare the home lighting CFL’s but they do compare to actual CFL grow light bulbs. Compare how many watts it takes of CFL lighting to equal one 400-watt HID. Then try to tell me that many or most CFL users use enough of their Wal-Mart, Lowes, Home Depot home lighting CFL’s to equal HID lighting.

It takes 662.5 total watts of CFL lighting to put out the same amount of usable light that a single 400-watt HID light puts out. Does that sound all that efficient to anyone here?
　
Based on the descriptions and pictures of CFL grows I have seen and read about over the years I would say few use enough CFL lighting to equal HID lighting and when they do they are actually using more wattage than the HID lighting would use.
　
Of course the heat issue argument can always be raised but if you want to compare the amount of usable light put off by different forms of lighting the attached chart explains it in a way that anyone should be able to understand it.

Like i said, for you maybe it's worth it, but i veg fine with HPS. It's not worth it for me to spend around 100 per bulb to duplicate all my lights, especialy since i do not have a long veg period. the ends do not justify the means.


CMH is the only way my plants will ever get that extra spectrum

Pumert said:

but what effects does a MH have on a plant if its just used for vegetative growth??

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I have used both MH and HPS and used both at the same time during flower. Right now I am only using MH and if I were only able to choose one to grow it would be MH. On my last grow I used MH with and LED panel for supplemental side lighting and found it worked as good as MH and HPS at the same time with a lot less heat.

just get a switchable ballast, and get a 30 dollar MH bulb