So you're ready to get a MH/HPS grow light? Perhaps you want to upgrade to an MH/HPS light from your existing setup, or maybe this could be your very first grow light for growing cannabis. 
What is HID grow lightssamsung 301h led grow light?
MH/HPS is a great choice for growing cannabis! This type of grow light has been the "golden standard" of indoor growing for decades because they work so well at delivering fast growth, big yields and dense, potent buds! They are easy to use and there's an abundance of information, guidance and other types of help for MH/HPS growers.
MH grow lights stands for "Metal Halide" and HPS stands for "High Pressure Sodium." These are two specialized types of bulbs that are great for growing plants, from a class of lights known as HID Grow Lights (High Intensity Discharge).
MH grow lights appear blue and are often used in the cannabis plant's vegetative stage (first stage of life). HPS lights appear yellow and are often used for the flowering stage (second stage of life). Either type of bulb can be used for the entire cannabis plant's life span, but HPS grow lights are better for the flowering stage. Many grow light ballasts allow you to use both MH and HPS in the same hood/reflector-just take one bulb out and plug in the other bulb-you' re good to go!

These lights are bright! While MH bulbs give off blue light, HPS bulbs like this one give off bright yellow light, which happens to be perfect to get plants to grow buds during the flowering stage.

Do I Need HPS or MH Grow Bulbs?

The short answer: get both!
High Pressure Sodium (HPS) bulbs emit a yellow-orange-red light, which is ideal for maximizing yields during the flowering cycle, but results in weaker plants if used during vegging.

Metal Halide (MH) bulbs emit a bluer light that makes for strong plant growth during vegging, but produces lower yields during flowering.

It is possible to use either of these bulbs on their own throughout the full grow cycle, but your results will be better if you combine the two.

Here are the different options, from best to worst:

BEST RESULTS: use MH and HPS bulbs at the same time

Plants grow best when they get both red and blue spectrum light through all growth stages.

That said, for most growers, we would not recommend this, as the cost increase does not justify the slightly better yields.

If you do want to run both bulbs, we recommend using HPS samsung 301b strip bubs overhead as the primary light source and supplementing them with MH bulbs (or blue-spectrum fluorescent bulbs) hanging naked (without a reflector) between the plants.

Alternatively, you could use MH bulbs as the primary lighting throughout the grow and add in HPS light during flowering to boost yields. This would be a bit cheaper to run, but plants would grow faster and stronger with the previous method.

GREAT RESULTS: use MH during vegging and HPS during flowering

This is the most popular combination, because modern digital ballasts allow you to use the same reflector and ballast to run both HPS and MH bulbs. All you have to do is switch out the bulb and keep growing.

This is what we recommend. And luckily, almost all grow light kits are available with both an MH and an HPS bulb.

DECENT RESULTS: Use only HPS bulbs throughout the grow

If you're going to use only one bulb for the whoe grow cycle, HPS bulbs are better. They might not be great during veg, but they produce by far the best yields during flowering.

WORST OPTION: Use only MH bulbs throughout the grow

Using metal halide bulbs during flowering will not result in great yields, making this the worst option.

Wattage

We'll try to limit this subchapter to 250 watts and 1000 watts since outside of that range is certainly inefficient to be used in indoor growing.

For average growers, you must use 400-600 watt bulbs because 1000 watts is quite hot. Though of course, you can pick this amount of wattage if you can manage the heat it produces.

But what I really want you to do is to use several fewer watt bulbs than picking up those with high wattage because it is more efficient.

Use 250 watts for 3-5 plants and distance them from the Canopy 6 inches to 8 inches.
Use 400 watts for 6-9 plants and distance them from the Canopy 9 inches to 12 inches.
Use 600 watts for 9-12 plants and distance them from the Canopy 12 inches to 18 inches.
Use 1000 watts for 12-16 + plants and distance them from the Canopy 18 inches to 26 inches.
What HPS Reflector Style Is Best?

This depends on your needs. We'll cover the pros and cons of each HPS reflectors type below. That should help you choose the best one.
Pros

the cheapest reflector
largest coverage
no glass to refract any of the light
no ducting needs to be run through light fixture
Cons

all the heat from the bulb goes into the grow room
front and back ends are open, so some light escapes and is not directed onto plants
Who is it for?

growers on a budget
large grow rooms (10+) lights where ducting makes no sense
growers who want to ventilate the whole room and not each individual light
Cool Hood Reflector
Pros

can hang closer to plants
focused light penetrates deeper below canopy
heat from bulbs never enters grow space
Cons

focused light means smaller coverage (about 4×4 feet)
the glass cover refracts a small amount of quantum board 125w
need to run ducting to fixture
Who is it for?

small to medium sized grows in enclosed spaces (like a tent)
growers who want to vent out the heat before it enters the room
Summary
What I've listed has only beneficial matter as you will gain experience along the way of using one of them. Just compare them if you have doubts and conclude if it suffices your taste.
Goodluck!