MarsHydro Mars Pro II Series Epistar 400W LED Grow Light

MarsHydro Mars Pro II Series Epistar 400W LED Grow Light

By |2018-10-26T02:26:48+00:00August 5th, 2018|LED Grow Lights, Sponsored|4 Comments

On growers’ forums, when people ask about reliable, affordable LED lights the name MarsHydro usually comes up sooner or later—and rightly so. The cheaper, entry level lights are perfect for getting started or kitting out a large grow space on a budget. But what about the top of Mars’s range?

What do you get when you spring for one of Mars’s best lights, the Mars Pro II Series?

In this review we’re going to take a look at the full spectrum MarsHydro Mars Pro II Series Epistar 400W LED grow light, with separate Bloom and Grow switches. If you want to replace a 250W HID light and cover a flowering area of 2’x2’, you’ll want to read on.

And even if you want to cover a larger area… still keep reading.

Because lights in the Pro II Series can be connected together. And, of course, larger models are available—five of them, including a couple with CREE LED chips for that extra bit of quality.

Full disclosure: This is a sponsored post. MarsHydro asked us to help promote its eBay factory store. Since we know Mars lights are already popular with our readers and we’ve always written positively about them in the past, we were happy to agree to write a series of posts. Moreover, while we have been paid to write these posts, the content has been left up to us.

If you missed it, the first post in this series explained why you should be heading to the eBay store instead of Amazon (main reasons: it’s cheaper; some models aren’t available on Amazon). In this post, and in our previous post, we’re introducing you to some of MarsHydro’s best and most popular lights.

MarsHydro Mars Pro II Epistar 400W: What do you get for your money?

MarsHydro Mars Pro II Series 400W - Mars Pro II 80 Review

Buy on MarsHydro eBay Store

In a nutshell: intensity, even coverage and value for money. Even Mars’s flagship models are accessibly priced.

The Mars Pro II Epistar 400W (sometimes listed as the Mars Pro II 80), as its name suggests, packs 80 high intensity 5W Epistar LED chips.

Having LED chips from a respectable brand like Epistar is always a good start, of course.

And in addition to that, Mars sets the chips in reflector cups to ensure an even footprint and good spectrum mixing, with minimal light loss.

With no secondary lenses, too, there’s also less chance of chips burning out.

The chips are also zener-protected, so one chip failing won’t cause the whole light to fail.

Pro II lights are full spectrum, so you can use this one for all grow stages. When you turn on the Bloom switch, it adds plenty of red light (including infrared (IR)) for a good flowering boost.

And having separate Bloom and Grow switches allows you the possibility of saving some money on energy costs, as well as a little bit of flexibility in how you grow.

Unlike its other lights, the Mars Pro II Series are designed to be connectible with a flexible U connector. While not quite as handy as being able to daisy-chain the lights, this feature still makes it easier to hang multiple units and get the best footprint out of them.

Mars Pro II Series lights are connectable

Mars Pro II Series lights are connectible

Brightness and intensity

MarsHydro Mars Pro II Series 400W PAR values

PAR values for the Mars Pro II Epistar 400W

As mentioned, the Mars Pro II Series 400W is capable of replacing a 250W HID grow light, while drawing only around 170W at the wall.

But what about those all-important PAR figures?

  • 752 umols when hung at 12” (flowering stage)
  • 421 umols at 18” (veg stage)
  • 203 umols at 24” (seedling/veg stage)

By way of comparison, those are better figures than similar sized lights in Mars’s cheaper ranges of grow lights.

Or to put it another way, paying a few extra dollars for a Mars Pro II will get you that extra bit of intensity for bigger, tastier buds.

Reflector cups around the chips help ensure an even footprint without hotspots too.

Though much more directional than HID lights, LEDs do still need a little focusing to get the best out of them. So we think the slight efficiency loss from a well designed reflector is an acceptable trade-off. Especially as Mars use this method rather than lenses, which can sometimes lead to LEDs burning out.

Footprint diagram for the Mars Pro II Epistar 400W

Mars Pro II Epistar 80’s footprint

What else do we like?

Another big advantage the Pro II Series has over some other MarsHydro lights is a longer warranty—the Mars Pro II Epistar 400W comes with a 3 year manufacturer warranty, serviced by local repair centers (for most of our readers).

Here’s what we also like:

  • 50,000 to 100,000 hour lifespan
  • Spectrum includes infrared (IR) for higher yields
  • Quiet (49.8 dB), efficient heat management
  • Compatible with timers, for easy dark/light schedule management
  • ETL/CE/RoHS certified for safety—parts inside are fireproof
  • Comes with hanging kit, instructions and region-specific power cord

Any downsides?

Well, this light is that little bit more expensive than some of Mars’s other lights.

On the other hand, it is brighter than the equivalent cheaper models and the footprint is more even than the cheapest. So you do get value for money.

Some growers would probably prefer dimmers for that extra bit of control over brightness and spectrum.

And some will prefer a light with UV.

UV light stimulates resin production, for more THC and terpenes. But UV chips are currently the least efficient and least long lasting LEDs and lights with UV tend to be a little more expensive.

Our overall verdict

The Mars Pro II Series is MarsHydro’s most expensive range of lights… but it’s still MarsHydro, so they’re still well within the price range of most growers.

And we think that extra expense is worth it, because it’s backed up by more intensity and a more even footprint.

Not to mention a longer warranty, should you need it. And the option of a couple of models with CREE LEDs.

As for the Mars Pro II Epistar 400W itself…

Like the rest of the Series, great value for money—and even better value if you buy it from the MarsHydro factory store on eBay.

About the Author:

MaryJane Farmer is the nom de plume of the writers for 420Beginner and the avatar for our brand (kind of like the Betty Crocker of Weed.)


  1. Mary Jane Farmer October 17, 2018 at 12:28 pm - Reply

    A comment from @bornfree didn’t transfer across when we updated the site recently, so we’ve reposted it below (our answer will follow):

    I’m looking for a good LED light and I want it to be cost effective. I’m new to growing. I got a cheap unbranded LED on eBay stated 300W but actual power is around 85W but for my next grow I want an upgrade. I’m growing a Sensiseeds Northern Lights auto right now. Just one plant but it’s filled out my 2 feet by 2 feet growing area. It’s in flower now and I have the light about 8 inches from the top of the plant. Since it’s an auto I run 18/6 lighting schedule. Is that the right way for auto in bloom?

    I’m thinking about getting a new light. A big factor for me is that it’s cost effective and I get the most grams of high quality bud per watt. I’m not growing for commercial use but I still want the best bang per buck (or £0. I’ll grow only one or two plants at a time. Electric is a big part of the cost in the UK so I was looking for LED lights with two switches for grow and bloom as well as dimmable lights using pulse width modulation. Unfortunately I can’t find a cheap light with all these features. Do you have any recommendations?

    Bestva have a 900W COB which is dimmable but it doesn’t have grow and bloom settings. It has a wide degree of light distribution so it could be hung lower with a lower light setting. i’m not sure about COBs though. lots of people like them because they emit white light to the naked eye but this means there must be some green light in the spectrum – much more than with conventional LEDs – so I worry they’ll be less efficient.

    For about the same price I can get the Mars Hydro pro 2 (the 80 is about £150) or the Mars hydro reflector (240 for £50 or 480 for £100 but it might be an older model).

    Then I came across a page comparing Mars lights and grams per watt.

    scroll down and you’ll see the best Mars lights significantly boost yields

    This could make a big difference if it’s genuine but how is it achieved? Is it just a marketing ploy? Platinum LEDs make similar claims about excelling at PAR per watt. The frequency spectrum graphs look very similar. Certainly not indicating huge differences between branded and unbranded lights. LEDs may differ in efficiency and I don’t know by how much. Reflector and lenses can all make a difference too but can these account for the massive differences in grams per watt?

    Obviously nutrients and genetics make a difference too but I’m thinking solely about the difference the light makes. I’m only growing one or two plants in a small area so I can use a lower wattage and keep the light low so I don’t think I need to spend a lot on a high power light. But electricity costs over time I think will be the biggest expense. (I’m currently growing in soil – Canna Terra Professional with added perlite and blood, bone and fish meal – with Floranova series and PK13/14 nutrients and Photosynthesis plus. I’ll be adding molasses to help the microbes do their job better.)

    Also – and this is a tough question – what about the law of diminishing returns? If i switch from the 85W light i have now to one that draws 170W true power will I get double the yield?

    Your advice would be appreciated.

    • Mary Jane Farmer October 17, 2018 at 12:36 pm

      Congrats, sounds like the grow’s going well! Quite a few questions and points to address there. So I’ll just start with an explanation of wattage and LED grow lights.

      When comparing LED grow lights wattage is really only relevant to your electricity bill. And it’s only the wattage drawn at the wall that you want to know. The wattage in the product name can refer to various different things, so can be a bit misleading.

      Different lighting technologies convert the watts drawn at the wall into light more efficiently than others, LED lights being the most efficient at doing so. So an LED light drawing, say, 160W might be more powerful than an HPS light rated at 300W. And to confuse things even further, some LED lights are of course more efficient than others, so our advice at 420 Beginner is always to ignore wattage as a measure of brightness or intensity when it comes to LED lights.

      What you need to look at is PAR values. PAR, as you might know, is photosynthetically active radiation, referring to the spectrum of light a plant can actually use for photosynthesis. “PAR values” generally actually refers to PPF or PPFD which is a measure of how many photons of light (µmols, or micromoles) in that spectrum are falling on your plants per square metre per second.

      Good manufacturers will provide charts/diagrams of PAR values with the light hung at different heights and how values differ across the footprint. PAR values are highest in the centre of the footprint getting lower toward the edges, but some lights give more even distribution than others. So that’s worth looking out for.

      Unfortunately, grams per watt, grams per joule and other measures of efficiency vs. yield are hard to find and rarely listed by manufacturers. So my advice would be to compare PAR values and wattage drawn at the wall, of the lights within your price range, and get the light with the best PAR values for the lowest wattage drawn. And if you’ve got any info about the light preferences of the strain you’re going to be growing, take that into consideration too.

      Regarding spectrum, blue and red light are obviously very important to cannabis plants, but the wavelengths in between also have some value. So don’t worry too much if there’s some green light included in the spectrum. It’s not wasted light, and I’ve yet to see any light that’s so badly balanced that it’s emitting pointlessly, inefficiently large amounts of green light.

      In other words, don’t discount COBs on the basis that they produce “white” light. So does the sun, and when wild cannabis gets enough of that it can grow to massive sizes!

      By the way, ultraviolet LEDs are the least efficient, so don’t worry too much about getting a light with UV in the spectrum. By all accounts, just adding in a cheap UV aquarium light during flowering will get you better results for less money then UV LEDS.

      For budget lights, the brands we tend to recommend are MarsHydro and Viparspectra. They tend to have better components and PAR values than many of the less established budget brands and you don’t see too many complaints about them from home growers. They mostly don’t have loads of features, but what they do, they do well.

      Speaking of features, you’re right about dimmer switches. Most so-called dimmers just turn off some of the LEDs, which could negatively affect evenness of coverage and energy efficiency. A proper dimmer switch that could dial up the red light during flowering could help your electricity consumption, but proper pulse width modulation dimmers are rare at the budget end. Viparspectra have some models available with dimmers, like this one, Cronus have some relatively cheap lights packed with features, and I seem to remember some Spider Farm lights having dimmer knobs.

      Also, bear in mind that there’s a lot of debate about whether you get better results from using a fixed spectrum for the whole grow (maybe adding in supplemental red and UV lighting during flowering) or using a light with bloom/grow or veg/flower switches. So maybe consider whether you definitely want dimmers. As far as I can see, which is the better method depends somewhat on what you want from your end product. For instance, if time is of the essence, not making a major change to the spectrum arguably gives you slightly quicker grow times, as the plants don’t need to adapt themselves to a new spectrum. Keeping a fixed spectrum and dialling up the red and UV arguably better mimics the sun when cannabis would naturally start flowering.

      Regarding autoflowers, 18/6 is fine. But you could even go to 24 hours of light, in theory. As you probably know, regular cannabis needs 12 hours of dark to trigger flowering and not revert back to veg, but autoflowering doesn’t need that signal. However, many growers argue that giving your plants a rest period will still be beneficial. Maybe research a bit more and test a different light schedule on your next grow.

      A quick word about DLI, daily light integral. I’ve explained it more fully in another comment on this post, but basically that refers to how much light a plant needs per day. For maximum energy efficiency, work out how many moles of energy per hour your light can emit and leave the lights on only long enough to give your plants what they need for the day. Moles per hour calculation would be: µmols x 60 x 60 / 1,000,000. (The µmols refers to the light’s PAR values.) Also, remember to calculate it using the PAR values at the correct hanging height for each grow stage, and add a bit of extra time to allow for the fact that PAR values will vary across the footprint.

      Regarding the merits of more expensive lights, what you’re usually paying for (besides extra features) is a higher quality of LED chips and certain other components, such as the driver. Often, higher priced lights have passive cooling, too, rather than fans. The best LED chip manufacturers include CREE, Samsung and Osram; and a name brand diode tends to be better, in general, than no-name diodes. Meanwell is a trusted brand name for drivers.

      Possibly the most efficient LED lights right now are quantum boards from Horticulture Lighting Group. They offer a great balance between price and power, with nice even coverage (more info at that link). To save extra money, you can buy them as kits or buy individual components and assemble them yourself. If you’re happy with that sort of DIY, there’s lots of info out there about assembling and customizing them. But you can also get pre-assembled, dimmable quantum board lights. We selected a mid-size light for our review, but there are smaller ones available too.

      To get more out of your existing light(s), have a look into plant training methods. You can use techniques like Low Stress Training, Sea of Green, Screen of Green, mainlining, topping, fimming, super cropping, etc. to create a more even canopy height, create more bud sites and expose more of the plants to the light. Same grow light, but more of its photons hitting your plant. Those kind of methods can be a great way to increase yields without extra expense (besides cheap things like plant ties and stakes). We’ve got a post on some of the most basic methods here.

      OK, I think that’s everything! 🙂 Hope it helps!

  2. J August 8, 2018 at 3:25 pm - Reply

    How many lumens per sqaure foot dont u need like so many to get a good yield not sure about par

    • Mary Jane Farmer August 10, 2018 at 7:47 pm

      Hi, J.

      Lumens are a measure of how bright a light is to human eyes. However, plants use and react to slightly more wavelengths of light than we’re able to see — what they use is called the PAR spectrum. PAR stands for Photosynthetically Active Radiation, which broadly speaking is the spectrum of wavelengths a plant can convert into fuel for itself through photosynthesis.

      Beyond each end of that spectrum there’s also ultraviolet light and infrared light, which plants don’t use for photosynthesis but which they do respond to in other ways. For instance, UV causes cannabis plants to produce more resin (and therefore more THC and terpenes) to protect from the UV rays, much like we’d apply sunscreen. Some lights include UV and/or IR, some don’t.

      Anyway, you’ll still find a lot of advice out there about lumens, because the spectrum of light that’s visible to us isn’t too much smaller than the PAR spectrum. So advice regarding lumens per square-foot isn’t totally without merit as a rule of thumb. However, although lumens and PAR are both measures of brightness, or a light’s intensity, PAR is just that bit more accurate.

      One final thing worth noting, usually when growers or manufacturers talk about a light’s “PAR values”, what we’re really referring to is a measure called PPF (or PPFD), which is how many photons of energy the light is emitting within the PAR spectrum per square meter per second. In other words, how many photons that it’s emitting that your plants can convert into sugars to store and use as fuel.

      This is measured in micro moles (µmols), one-millionth of a mole. Getting around 25-30 moles per day is good for cannabis; some commercial growers aim for 30-40 as the absolute optimum. But anything above 40 is generally agreed to be wasted light. Light requirement also varies a bit from strain to strain — your seeds may even come with advice about Daily Light Integral (DLI), which is roughly speaking how much light you need to give that plant per day.

      If we do the DLI calculations for this light:

      During flowering (i.e. a 12 hour day), it should give you 32.49 moles per day (752µmols * 60 * 60 * 12 / 1,000,000).

      And during veg, with the light hung a bit higher, over an 18 hour day, your plants will get 27.28 moles. (Although, in both cases, at the edges of the footprint, the numbers will be lower.)

      Finally, the crucial thing to pay attention to is whether a light can give your plants enough moles over a 12 hour period when hung at the recommended height. Because, during flowering, you won’t be able to compensate for a less powerful light by simply leaving it on a bit longer.

      [EDIT: Some growers actually don’t grow with a 12/12 light/dark cycle during flowering. The theory is that the 12 hours of darkness is the crucial thing that makes cannabis start flowering and keep flowering, so they give the plants 18 hours of light (for instance) followed by 12 hours of dark. The idea being to give plants even more energy for flowering and create bigger, better yields. In other words, when you can completely control night and day by growing indoors, you’re not necessarily constrained to 24 hour days — which could let you get more moles out of a lower power light, but at the expense of longer growing times.]

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