A Detailed Look into the Mars Hydro SP-250

A Detailed Look into the Mars Hydro MH-SP-250

Let’s take a look at Mars Hydro’s SP-250 LED Fixture. The following is divided into the following sections:

  1. Introduction
  2. Shipping and Delivery
  3. Specifications (OEM specification claims)
  4. Construction
  5. Our Measurements
  6. Discussion (comparing the supplied specification and marketing to our measurements)


The LED lighting industry is something of a minefield with plenty of semi-accurate / semi-relevant information. It’s not entirely the manufacturer’s fault, mind you. Traditional lighting metrics were simply not designed to consider the needs of the horticulture industry and the industry standards associations have been slow to catch on. In many cases, the traditional metrics are next to useless. As such, metrics are evaluated under test conditions that when otherwise measured in the real world end-up showing a significant amount of variation and disappointment depending on the application. Or, metrics are provided that have little relevance towards horticulture that, rather, have been traditionally used for comparison purposes for lumenaires. The lumens, for example. To make things worse, because of this mish-mash of metrics and standards, some vendors in the space have opt’ed to conflate or mislead consumers by cherry picking metrics that look “good” or “go big”.

On the other-hand, the situation has been steadily improving over time with some vendors that specialize in the horticultural space doing their best to eliminate the cruft. Rather, they concentrate on the metrics that are most important to growers. Metrics that can be reliably reproduced even under varying conditions. This results in the customer knowing what they are getting. Rightfully so, these fixtures tend to be rather specialized and are typically pricey. The vendors that have followed this practice have become market leaders in their space.

Because of the confusing landscape of LED specifications and metrics, educated consumers have become something of LED lighting snobs and will carefully scrutinize any new vendor claims. Personally, in the past, I’ve preferred to concentrate on the ready-to-go “semi-pro” fixtures from the likes of Fluence Bioengineering, Heliospectra, P.L. Light, OSRAM, and their ilk. Their numbers tend to be reproducible on the ground. This builds trust.

And, for good reason. Light is a primary input into a plant and, as such, I have had little regret in ponying up a significant amount of coin to purchase reliable fixtures (well, maybe a little bit of regret). Fixtures from these vendors have been traditionally engineered and have proven to withstand the rigors of a growing environment. These fixtures have been designed for high efficiency through the utilization of the most modern LEDs available. They have been designed to safely operate for long periods around us ham-fisted personnel.

This brings us to Mars Hydro. Historically, Mars has produced fixtures in the “blurple” category of lights. “Blurple” being a nickname given to fixtures where the vast majority of the light output is concentrated in the blue and the red spectrum. This produces a very purple hue with little balance overall.

While plants may grow fine, such unbalanced spectra just doesn’t seem natural. Add to that the numerous studies that suggest there’s something much more to it than simply blue and red.

Photo Source

The newest offering from Mars, however, are broad spectrum with a radically different engineering effort when compared to their prior offerings. They’ve offered up interesting features and more thorough specifications to include information that tends to be useful in horticulture applications.

Photo Source

Night and day. They seem to be listening to their customers needs. I’m intrigued and have purchased a unit.

Let’s take a closer look at the MarsHydro MH-SP-250 and see how she stacks up.

Shipping and Delivery

The fixture was well packaged using expanded polypropylene foam all around. Wooden slats glued to the foam was included to protect the LED assembly.

They aren’t fooling around here. No styrofoam to be found anywhere:

Included in the package are a couple of captive hangers and ratcheting carabiners. While the hangers would be expected, the addition of carabiners are a nice touch:

Also included was a single page lamp specification.

I don’t know what it is. First perceptions matter I guess. They’ve taken some care in thinking about how this is important.

Having distributors located at strategic locations seems to help Mars to get a unit to you quickly, in a matter of a week in my case. They even contacted to let me know that shipping would be delayed by a day due to the Labor Day holiday in the US. Can’t recall the last time that occurred… Very nice of them…


The following are the manufacturer’s specification for the Mars Hydro SP-250 as taken from the included specification guide:

Specification Guide (click to expand)

Dimensions and Weight (click to expand)

Length: 42.52 inches (1080 mm)
Width: 3.54 inches (90 mm)
Height: 3.15 inches (80 mm)
Weight: 8.68 lbs (3.935 Kg)

AC Power Consumption (click to expand)

Operating Voltage: 100-277 VAC
Typical Current Draw:
1.930A @ 120 VAC,
0.9578A @ 240 VAC,
0.8387A @ 277 VAC

Operating Environment (click to expand)

Temperature: 5 - 104 F (-15 - 40 C)
Orientation : LED emission facing down

Spectrum (click to expand)

Ultraviolet : 380 - 410nm
Deep Red
IR : 730-740nm
White : 3000 - 3200K & 6000-6500K


Lifetime (click to expand)

LED expected lifetime : > 50,000 hours
LED expected output : > 90% at 50,000 hours
Warranty : Limited 3 year


The heatsink design is impressive. They’ve opt’ed to utilize relatively heavy 22 gauge aluminum for the fins and a design where each fin interlocks with each other fin and to the outer casing. This creates a solid and rigid structure.
The gauge is at least as comparable to some of the other OEM designs that I’ve seen (and own) that utilize a similar heatsink form factor. The interlocking design of the Mars heatsink is much better on this design, though. No issues on the construction here. We’ll check the operating temperatures a bit later…

I don’t know how they bonded the fins to the base but it looks fairly skookum (thank you AvE). I’m not sure if that’s a paint or a galvanized coating on the base between the fins:

Cable ingress:

Nice and proper nylon washers in the right places:

Weather / Ingress protection / IP65

Mars Hydro claims this model has an IP65 rating. What this denotes is that the assembly has been tested for protection against and to safely operate in a specific environment. The two digit number “65” indicates the level of protection and follows the following format:

Image Source

(6) No ingress of dust; complete protection against contact.

(5) Water projected by a nozzle (6.3mm) against enclosure from any direction shall have no harmful effects.

This is a nice feature potentially making this model useful in environments with hired personnel and greenhouse like conditions. The home hobbyist and DIY’er may scoff at this feature as being useless to them while others that have an eye towards safety will find this feature comforting against the occasional misdirected water spray.

Conformal Coating

The LED PWB has been conformally coated by Mars Hydro. Conformal coat simply means that a protective substance is layered onto the PCB and the components after assembly. This has several distinct advantages including the protection against moisture damaging the electronics.

This is what the coating looks like from an angle:

This is a nice coating and they’ve done a great job in application. Although, this is the first time I’ve come across a conformal coat quite like this. It is soft and elastic and has the feel of a silicone resin / siloxane material:

Liquid Tight Fittings

The interconnects between the mains supply and the interconnects between the power supply and LED arrays are all spliced using liquid tight fittings.

These are not socket/plug fittings but rather splice fittings where cable terminations are screw clamped into place.

These splice points will allow you to extend cabling with a similar diameter cable without having to cut into the OEM cable. The splice fittings are not waterproof but are instead “water tight”. This type of fitting should be more than sufficient to meet the manufacturer’s IP-65 specification. These are a nice feature.

FWIW, Mars Hydro did tin the wire termination with solder which shows good practice and attention to the details that are typically hidden from sight.

Here is a photo of a temporary splice extension that is easily undone for the DC power measurement detailed later:

Power Supply Ingress Rating

The included Meanwell ELG-240-36A is rated by the manufacturer to IP65.

Power Supply

The power supply utilized for the SP-250 is a Meanwell ELG-240-36A. Meanwell has been well vetted in this space.This would be considered a quality power supply.

One interesting item to note is the listed output power capacity for this supply. The label indicates that it is capable of delivering 180 Watts from 110VAC sources and ~240 Watts from > 200VAC. We’ll circle back and look at this in more detail in the discussion section.


This supply has a manually adjustable dimmer control accessible from bottom side of supply.

LED PWB Construction

Without taking the unit apart, the PCB is likely an aluminum core laminate which would be typically used in high power applications (such as this). Aluminum core PCBs improves the movement of heat away from the LEDs and over to the heatsink. A white solder mask is applied to the finish which is a wise choice due to it’s relfectivity characteristics.

There are a few discrete passive components on the “top” side of the PCB. Namely, 0 ohm resistors. I do not know if there are any additional components located on the “bottom” side of the PCB at this time as I didn’t want to fully disassemble the fixture. It would be interesting to do a full tear down but I’d like to utilize this lamp. Perhaps in a future episode.

The amount of solder paste (solder) used to reflow the components is likely sufficient although, in this case, there is not enough solder applied to fully wet the copper pad. That doesn’t necessarily indicate a flaw as the science behind making a reliable joint can be counter-intuitive particularly for fixtures that undergo reoccurring hot/cold cycles (thermal stress). It takes a certain amount of tuning between the manufacturing process and stress testing to get the ratio dialed in. Too little or too much can result in stress cracks (eventually leading to intermittent connections). I’m assuming they’ve tuned their process for reliability.
Overall the PCB reflow looks clean and modern.

Let’s turn her on:

When looking to determine which Epistar LEDs were utilized, we can try to catch a glimpse of the individual die and compare this to the manufacturer’s data.

The color pallete (click to expand)


Far Red?:


White / Yellow:

White / Blue:


I didn’t spend much time looking through the datasheets comparing the die in the above color pallete photos and, as such, was not able to find exact matches for most of these on Epistar’s publically facing website. That doesn’t mean they don’t exist, that the datasheets show accurate die diagrams, or that these aren’t custom / unlisted. If anyone would like to dig in or if Mars would like to share the info, it would be interesting to know which of the various Epistar devices are being utilized.


AC Power Consumption (no dimming)

Measurement Instrument : Fluke 43B Power Quality Analyzer (click for details)

Instrument : Fluke 43B
Type : Multi-meter
Measurement Range: Voltage 5.000V to 500.0V, Current 50.00A to 500.0kA
Accuracy: Voltage ±(1 % + 10 counts), Current ±(1 % + 10 counts)
Calibration Source : Manufacturer

Measurement Instrument : Pico TA189 Current Probe (click for details)

Instrument : Pico TA189
Type : Current Probe
Measurement Range: 0-30A
Accuracy: ± 1% of reading ± 2mA
Calibration Source : Built-In

Average current draw (120.0VAC) ~1.886A (click to expand)

Power Consumption (120.0VAC) 225W with a Power Factor (PF) of 1.0 (click to expand)

Harmonic Content (THDr) 10.2% (click to expand)

DC Power Consumption (no dimming)

Measurement Instrument : Fluke 43B Power Quality Analyzer (click for details)

Instrument : Fluke 43B
Type : Multi-meter
Measurement Range: Voltage 5.000V to 500.0V, Current 50.00A to 500.0kA
Accuracy: Voltage ±(1 % + 10 counts), Current ±(1 % + 10 counts)
Calibration Source : Manufacturer

Measurement Instrument : Pico TA189 Current Probe (click for details)

Instrument : Pico TA189
Type : Current Probe
Measurement Range: 0-30A
Accuracy: ± 1% of reading ± 2mA
Calibration Source : Built-In

DC Voltage and Current Draw

As measured at the output of the Meanwell power supply:

Power Consumption (click to expand)

As measured at the output of the Meanwell power supply:

Calculated Supply Conversion Efficiency: 92%

Temperature (no dimming)

Measurement Instrument : Fluke 80T-150UA Universal Temperature Probe (click for details)

Instrument : Fluke 80T-150UA
Type : Temperature Probe
Measurement Range: -58 to +302 °F
Accuracy: ±1.8°F from +32 to +212°F
Calibration Source : Manufacturer

Measurement Instrument : Flir A35 Thermal Camera (click for details)

Instrument : Flir A35
Type : Thermal Camera
Measurement Range: -25°C to 135°C (-13 to 275°F) / –40°C to 550°C (-40 to 1022°F)
Accuracy: ±5°C (±9°F) or ±5% of reading
Calibration Source : Self / Manufacturer

Operating Temperature

Beginning Surface Probe Measurement: 77.4°F ()
Power supply case at 1.5 hours: Surface Probe 129.5°F ()
Heat sink fin at 1.5 hours: Surface Probe 116.3°F ()

Hotspots: Some regions of LEDs show hotspots (click to expand)

Hotspots, false color images, @1.5 hours non-dimmed

Thermal Image of Operating Assembly (click to expand)

Fixture thermal image, false color image, @1.5 hours non-dimmed

Lighting Metrics

Spectral Power Distribution (SPD)

Measurement Instrument : Stellarnet CXR-SR-100 (click for details)

Instrument : Stellarnet CXR-SR-100
Type : Spectrometer
Bandwidth : 220 to 1100 nm
Resolution : 4 nm
Optical Fiber : F600 VIS/IR
Sensing Head : Cosine Corrected Adapter CR1
Calibration Source : Stellarnet SL1-CAL (300-100nm) Tungsten-Halogen Lamp

18 inches from fixture, open air, center spot, 30 minutes to stabilize (click to expand)

Center Point, Open Air Measurement:

Spectrometer and Quantum Sensor Cosine Heads:

Spectrometer Electronics:

Spectral Distribution :

Blue(400 - 500nm): 15.4872%
> Green(500 - 600nm): 43.8039%
> Red(600 - 700nm): 40.7089%
> Total :100%
UVB(287-320nm): 0.00759645%
> UVA(320-400nm): 0.140558%
> Violet_Blue(400-475nm): 13.1032%
> Cyan_Green(475-550nm): 17.2152%
> Green_Yellow_Red(550-700nm): 65.0914%
> FarRed_NearIR(700-850nm): 4.44204%
> Total :100%
Spectrum Plots (click to expand)

Captured Spectrum

PAR / YPF overlay

Radiant Energy and Ratios

The following metrics details the measured radiant energy 18 inches from the fixture, open air (no nearby reflective walls), center spot (at the center of the fixture), after allowing 30 minutes for the fixture to stabilize:

Integral radiant (400-700nm): 102.213 W/m^2
Integral radiant (350-840nm): 106.0 W/m^2 
Lumens (m^2) : 33534.23
Spectrometer PAR (400-700nm): 484.463 umol / m^2 s 
Quantum Sensor PAR : 451.6 umol / m^2 s
YPF (360-760nm) : 433.314 umol / m^2 s
YPF/PFD: 0.89
PSS: 0.85
DLI index [12 hours] : 20.93
PAR Max :1.34342 @595.073 nm

Output Stability

Output power as measured with the Apogee Quantum Sensor over an ~80 minute period from power-up shows a small amount of variation of ~2% as the unit heats up. Measured 18 inches from fixture, open air, center-point.

Variation (click to expand)

Output Stability Plot: Delta 460.4 to 451.6 uMols/m^2 s

Color Quality

The following graphs details how the human eye will perceive colors that are illuminated by the fixture. This has little to do with the quality of light as perceived by the plant but rather how easy it is for humans to discern colors or how accurate the colors in a photograph under illumination will appear.

Chromaticity 3750K (click to expand)

CCT: 3750
Chromaticity Coordinates: (x=0.39079, y=0.37253)
Dominant Wavelength: 601.5nm
Purity: 29.49%

Color Rendering Index 78.06 (click to expand)

NIST CRI: 78.06

Color Quality Scale 75.76 (click to expand)

NIST CQS: 75.76


Measurement Instrument : Apogee Instruments SQ-250 (click for details)

Instrument : Apogee Instruments SQ-250
Type : Quantum Sensor
Bandwidth : 389 to 692 nm ±5 nm
Resolution : 0.1 µmol*s / m^2
Sensing Head : 2PI Cosine Corrected
Calibration Uncertainty : ±5%
Calibration Source : Manufacturer Calibration
Source Correction Table :

Not measured.

Manufacturer’s Warranty

Specification notes a limited 3 year warranty.



How does the supplied specification measure up to the results we are seeing?

:white_check_mark: Number of LEDs

Specified : 684
Measured :
Comments: Perfectly matches specification.

:white_check_mark: Power Consumption @ 120VAC

Specified : 224 Watts ±5% (website states 245 Watts ±5%, though)
Measured : 225 Watts
Comments : Matches specification. Would be perfect if the website didn’t claim a different number.
Additionally, the DC power measured at the power supply output was measured at 207 Watts. This is the true power being delivered to the LED array after the 92% conversion efficiency of the Meanwell supply.

:white_check_mark: Power Factor

Specified : 0.9954
Measured : 1.00
Comments : Perfectly matches specification. Measured better than specification.

:white_check_mark: Temperature

Specified : N/A
Measured : Power Supply@129.5°F (54.16°C), Heat Sink Fins@116.3°F (46.83°C), Ambient@77.4°F (25.2°C)
Comments : Good. Power supply shows highest temperature. The maximum case temperature for the power supply is specified at 90°C and the measured temperature is well within the operating range. Some regional hotspots have been noted to exist on the LED face. It is not known if the existence of these hotspots have been factored in by the engineering team or if they could pose a reliability issue.

:white_check_mark: Spectrum

Specified :

Measured :

Comments : Can’t make an exact comparison since the source data is not available. Nominal differences exist possibly due to measurement apparatus (sphere mixing vs open air) but in general these appears close enough to call this a good match.
You can find some comparative spectra for other fixtures and lamps that we’ve measured in the past, here:
Lighting Spectral Data

:warning:Radiant Energy

Specified : 632 or 448-500 uMol/m^2 s
Measured : 484.463 umol / m^2 s open air (400-700nm)
Comments: Here is where things get tricky. In the specification, the PPF / PPFD varies depending on where you look. They’ve performed some testing on the unit with what I believe to be an integrating sphere. An integrating sphere is an excellent and expensive tool for determining the total number of photons produced by a fixture. Such a test tool is used to capture ALL of the light emitted from a light source even if the photons were somehow emitted tangentially from the fixture. It is the optimal output measurement of a fixture. It is also good for measuring the overall spectrum since it, in essence, mixes the varied energy photons (colors) prior to measurement (otherwise there may be mild variations in spectra depending on the measurement sensor location). From an integration sphere you can determine the overall efficiency and spectrum but not necessarily the real world performance (amount of light in a specific direction) since the optical characteristics are not measured. For that, you’d either perform real world tests or by model simulation.

So, here are a couple of notes to consider for what they’ve specified as 632 uMol/m^2 s:

It appears that the unit under test (via the integration sphere) is consuming 233.1 Watts and, as a result, will produce a higher luminous output than what we’ve experienced (225 Watts). This means that their test unit is likely running off of 277VAC as opposed to 120VAC. This produces a higher output than a US based fixture would be capable of due to the installed line cord being designed for 120 VAC. You could potentially install different cabling and supply a single phase off of a three phase drop to obtain a similar 277VAC.

Second, it appears that they’ve extrapolated the PPF from the integrating sphere measurement. E.g. by simulating the values. They’ve calculated an optimal PAR (PPFD) output by, as they’ve put it, “adjusting” the PPF measurement.

The integration sphere measured 562.88 uMol / m^2 s while the “adjusted” uMol / m^ s that simulates a measurement at 18 inches from the unit is calculated as a higher number of 632 uMol / m^2 s. I don’t really understand this calculation or the reason why the total PPF would increase rather dramatically relative to the measured integration sphere values. Perhaps Mars could provide some technical insight? I’d think this number should be more inline with the “actual” table that denotes a PPFD between 448-550 uMol / m^2 s. Somewhere around say, 494 uMol / m^2 s?

They’ve also opt’ed to use the “adjusted” value to generate what appears to be a simulated PAR map. This assumption is based on the their center point measurement matching the “Measured in adjusted uMol / m^2 s …” of 632 uMol / m^2 s.

Otherwise, the PPFD we’ve measured (484.463 umol / m^2 s) is within the PPFD listed in the “actual” table in their guide. This was measured without any reflective walls (open air) and would likely increase a nominal amount if reflective materials were employed.

I’d agree their PPF value from the integration sphere as being accurate for 277VAC, it is not necessarily accurate for the 120 and 240 VAC conditions (which they do not specifically indicate when listing the specification). Additionally, I do not currently agree that the “adjusted” PPF value or the PPFD map as being accurate simply because I do not understand how they came to this conclusion. I do agree that the PPFD values listed in the “actual” performance tables as being accurate since it matches our current experience.

:white_check_mark: PPE

Specified : 2.57 umol/J (actual table indicates range of 2.4 to 2.57). @233.1 Watts
Measured : 2.15 umol/J. @225 Watts
Comments : Accurate PPE values are made using an integration sphere which I’d assume is the case here. These are optimal measurements. You can expect estimating such values in the field, such as using PPFD, to be measured at something less. We’d calculate a PPE of 2.15 when using the centerpoint spot measurement method with the measured 225 Watts power consumption at the wall. This does not match the specification or the “actual” numbers but is still a good number. Since I don’t have the equipment to accurately capture the entire flux, I’m giving this a green checkmark since we are close enough for hand grenades and I can’t properly assess the accuracy.

:warning: PAR Mapping

Specified :

Measured : Not measured at this time, conflicting information.
Comments : For the same reasons as detailed in the Radiant Energy comments, it appears that Mars derived these numbers from a simulated model. What they are calling “adjusted” uMol / m^ s is based on the integration sphere PFD. As such, I do not feel this mapping would be accurate for actual use. Further, the lengthwise dimension of their map doesn’t seem to correspond to the dimensions of the actual fixture. E.g. the fixture length is 47.5 inches while the maximum length of the provided PAR map is 36 inches. Because of this, it is difficult to know what is actually being conveyed in their mapping and whether it has any relevance to the suggested bloom area of 2ft x 4ft and, likewise, the specified veg area of 4ft x 4ft.

:white_check_mark: Chromaticity

Specified : 3900K
Measured : 3750K
Comments : Same as with the spectrum. A nominal difference in the values exists possibly due to measurement apparatus (sphere mixing vs open air) but in general they appear close enough to call this a good match.

Things we didn’t specifically measure but could use your help with filling in some of the details:

Ingress Protection (click to expand)

We didn’t measure against the IP65 rating. There are three primary engineered features that address the IP-65 ingress protection

  1. Conformal Coating
  2. Watertight electrical interconnects
  3. IP-65 rated power supply

I’m not really familiar with silicone resin / siloxane conformal coatings but I’ve noted a couple of potential advantages and disadvantages:

  1. Advantage : Moisture / humidity and dust protection.
  2. Advantage : Some protection from accidental contact with live (DC>19V) voltages.
  3. Advantage : Mild impact protection.
  4. Advantage: Relatively easy to clean.
  5. Advantage : Diffuses / spreads the light energy to some extent.
  6. Disadvantage : May absorb a small amount of the light energy. Unclear if it absorbs UV.
  7. Disadvantage: Difficult to DIY rework / repair.
  8. Possible disadvantage: Depending on the chemistry of the coating, there could be long term yellowing / hazing of the clear coating. It is also unclear if, overtime, heat will allow foreign material to bond to the coating.
  9. Disadvantage: While being easy to clean, it is at the same time also more difficult to clean. The surface is “grippy” and tends to hold onto particles. For this particular unit, despite having wiped it several times, dirt particles tend hang around. The particles are not bonded in place, it’s just a grippy surface.

For UV, this paper tends to indicate that most silicone resin conformal coatings are resistant to UV aging,

Length and Weight (click to expand)

Specified Length : 42.51 inches (1080 mm)
Specified Width :
Specified Height :
Measured Length : 42.5 inches (1079.5 mm)
Measured Width :
Measured Height (w/power supply) :
Weight :
Comments :

Warranty (click to expand)

Mars Hydro has been promoting a three year extensive warranty. Now, I’ve been around for awhile and having a warranty exclaim “extensive” seems rather vague. “Extensive” is not really a legal term so what does this really mean?

They have a flow-chart, let’s take a look :

Warranty Flowchart (click to expand)

Flowchart hyperlinked from Mars Hydro at https://www.mars-hydro.com/mars-hydro-warranty

Ah, the notice in the bottom right box of their flow-chart explains.

A unit is fully covered including shipping charges for the first 90 days. Between 90 days and 1 year, a unit is covered against defects and Mars will cover parts and repairs but you are responsible for any shipping costs. Beyond 12 months we are into DIY land where the OEM will either supply replacement parts or you can pay the full-boat for repairs. Since some of the componentry on this unit are encased in a conformal coating on a heat sinking base, it would really be an “advanced” DIY’er project to reflow an LED, for example.

Customers generally don’t like surprises. From the stand-point of a consumer purchasing a finished unit, this is really a one year warranty. Exclaiming a warranty as being extensive may actually trigger an implied warranty depending on locale. Mars Hydro should call it what it is across their marketing efforts, a one year full warranty along with a three year parts warranty. In their own specification guide that ships with the lamp (not on-line), it’s instead called a “limited 3 year” warranty.

Note: The marketing definition appears fluid as Mars seems to be updating and clarifying how the Warranty terms are conveyed. The above flow-chart is what you should refer to when assessing the manufacturer warranty claims.


This is a rather nice fixture. It is rigid, well engineered, and has a robust feel to it. The specifications provided in the shrink wrapped specification guide are relatively accurate with the possible exception of the derived PPF numbers. Subsequent “actual” single point PPFD numbers in the examples table does align with our experience.

With the IP-65 rating, we now have a candidate unit to use around the bumbling hands and spooky wet works. While, Mars Hydro has correctly specified IP65 in the shrink wrapped specification guide, depending on where you look, the marketing claims/FAQs oscillate between stating that this unit is waterproof versus not waterproof. The correct statement is “rated to IP65”. This means that the unit is not “waterproof” but, instead, is protected against water ingress by low pressure water spray.

This unit remains cool enough to handle with bare hands under moderate ambient temperatures. It’s much cooler than I would have expected overall. The Meanwell power supply is the warmest component measured. On that note, the DC power measured at 207W which exceeds the rated power of the supply (180W). This is 115% of the rated load with no dimming. Since the current (dimming) is controlled by the supply directly, I’m not certain if Meanwell has underspecified the power capability of this device but the maximum case temperature (90°C) should be appropriately de-rated to compensate. Which, Mars does with an environmental rating of 40°C maximum.

The supply dimmer is something of a PITA as configured. You’d really only be able to adjust it when the unit is off-line since it is difficult to access the controls. Or, if you were to remove the supply from the chassis and extend the cabling (which might be a good idea, anyhow), access to the dimmer would be easier and you’d save a little on any heat load in the grow area.

Personally, I would have rather seen a pigtail interconnect for an 3 in 1 dimming function allowing for remote control. An example supply with remote dimming while retaining an IP-65 rating is the Meanwell ELG-240-36AB versus the included Meanwell ELG-240-36A.

This unit produces a moderate amount of PAR useful for a 2 foot x 4 foot area with an estimated DLI of about 21 over a 12 hour period directly under the unit. Whether a DLI of 21 is sufficient will depend on your personal growing style and needs. With the rather slim profile of the unit, it would not be difficult to increase the DLI by utilizing a number of units in close proximity.

There are a couple of hotspots discovered on the face of the LED PWB but it is not known if this could indiciate a reliability concern. Reliability overall is not really known at this time but from the engineered feel of this unit, I have high hopes.

On reliability, Mars Hydro has not been without their issues in the past. They’ve purported the use of (mostly) Epistar brand LEDs in the gull wing style packaging in their past products and have been haunted by some reliability problems to include failed LEDs. It is not clear if that issue lay with Mars or the LED manufacturer.

With the newer generation Epistar LEDs in a more modern packaging on their new products, they are claiming >50K hours at >90% luminous flux output. Epistar, unfortunately, does not seem to publicly provide reliability data in their datasheets and, as such, it is difficult to confirm this claim. UV LEDs, traditionally, have had lower lifetimes than non-UV LEDs so it would be interesting to learn more on how Epistar has tackled this problem. 50K hours >90% is a heck of a long time assuming that the utilized LEDs live up to that specification at temperature. Time will tell.

Mars Hydro does provide a warranty which they have been marketing as a three year warranty. They seem to be hoping that this will convince you that their new line of products are significantly more reliable and with less risk of failure. There is some detail work here to consider, however, as the warranty really only covers costs for the first 12 months and the user would have to cover shipping after the first 90 days. Replacement parts are provided for up to three years through an RMA process if you are willing to pay for the repair labor or perform the repair yourself. If you are capable of holding a screw driver, replacement of failed components (really only the power supply) would not be difficult with the exception of the LEDs / LED assembly.

How are the economics? A similar form factor Fluence Vypr 2p which would run in the $1600 USD range is specified as producing a PPF of approximately 1700 umol/s. This is about $0.94USD per umol. The Mar Hydro is specified as producing a PPF of approximately 563 umol/s and costs approximately $260 USD. This is about $0.46. Around half the cost when simply comparing against the umols of output.

Let’s discuss PPE for a moment. Photosynthetic photon efficacy (PPE) is the amount of total photons being produced as compared to the amount of electrical power consumed. In order to accurately calculate the PPE we need to be able to capture all of the photons produced and, in order to do that, we would need a specialized piece of gear called the integrating sphere. A larger PPE number indicates a more efficient fixture where the theoretical maximum is around a PPE of 5.1. Such a high PPE is not likely anytime soon but a variety of vendors have been approaching a PPE of 3.0 for broad spectrum illumination by using the most advanced commercially available LEDs.

We should note, the majority of the measurements we’ve made in order to compare against the supplied specification are being made at the center-point of the lamp at an 18 inch distance. The center-point is an optimal measurement location since the reflectivity of the surroundings has little affect. It is also typically the location with highest amount of irradiation from the fixture. This is a fair external measurement location to compare against a specified integrating sphere measurement (which we do not have) for PPE. But…

I’ll also note, a different technique beyond the center-point measurement is employed for PAR mapping where PPF/PPFD is measured at equal intervals over the illuminated area by moving away from the center of the fixture. Such measurements gives you an averaged PPFD over the area and will typically a result in a smaller PPFD value as a whole. In such measurements, however, the environment does come into play, namely, the location and reflectivity relative to the enclosing walls. Such measurements end-up being bound to the specifics of the measurement space. We have chosen not to produce a PAR mapping (and an averaged PPFD) at this time for this fixture, in part, due to an unclear definition of this fixtures supplied PAR map along with the missing definition of the measurement space.

Back to the comparisons. For the same two fixtures, the Fluence fixture claims a very high PPE of 2.7 while the Mars Hydro fixture claims a PPE of an also impressive 2.5. As noted earlier, accurate PPE values are made using an integration sphere which I’d assume both manufacturer’s utilized. Those are optimal measurements that are generally not realizable in practical use (light is lost and absorbed by the surroundings). They do provide in the examples table (in the supplied guide) that if you were to take three of these units, the PPE somehow exceeds the theoretical maximum at an incredible 7.20 to 8.88. Mmmm, no. The math really really doesn’t work that way.

We’ve calculated an estimated PPE of 2.15 when using the centerpoint spot measurement method with the measured 225 Watts power consumption at the wall. While, this does not match the specification or the “actual” numbers, it is still a very good number. The improvement in this area is commendable. If we were to consider the actual DC power consumed by the LED array (ignoring the 8% power supply loss), the PPE of the array itself would weigh in at 2.34 (for our measured 484.463 umol / m^2 s @207 Watts using the centerpoint spot measurement). If they were to utilize OEM high bin grade LEDs from vendors such as Samsung or Cree, it could lead them to producing a unit that is in the top tier for efficacy, albeit at a slightly higher price point :wink: With Epistar, a PPE greater than two is still a very good number.

This is a unit that is ready to use. Despite my being picky about some missing clarity on how they specify and market this unit, I am rather pleased with this fixture and, frankly, it has exceeded my initial expectations. The daily light output for a single unit may or may not fit your needs. With the thin profile, the potential for multiple units in the same space allows for flexibility in designing your grow area and increasing the overall DLI. Particularly, if you want to push the intensity hard or plan to employ CO2. But in order for us to do that, Mars does need to correct their PAR mapping using the more realistic “actual” numbers as opposed to what appears to be derived/calculated values. They have taken some care across the board and have not skimped on some of the hidden details that I had looked for. At the listed price point, this does appear to be a worthy fixture. After some additional hands-on use, I do look forward to purchasing another.



Incredible amount of information! Thank you very much for thorough analysis and testing!


Damn! Were you already doing this before they became a sponsor?


No, I had purchased this particular unit shortly after they became sponsors of OG. I didn’t really keep track of their product portfolio prior to that point. But this particular unit caught my eye and I wanted to get a better feel as to what was going on, it’s an honest assessment from my viewpoint…


Excellent write up thank you for your time and test results posted for the community to read.


Amazing, in-depth review @Northern_Loki and some nice results too! Thanks for sharing your findings!


Really well done review…pro! I’m impressed by this light it definitely looks alot better than I expected from a ‘cheap’ grow light. The waterproofing is a really cool feature.


Very happy to see this review! It was a lot faster than I expected! This was very well written Loki, and I appreciate you investing your time and money into doing this for all of us. It was pretty much as I expected, misstated numbers and all, but wasn’t as much of a difference between stated and actual as I thought it would be. I still don’t agree with their business practices, and won’t be a customer, but I do feel that they could be a welcome option, in their latest models only (blurples be damned), to a complete novice.


Awesome job!! @MarsHydro_LED owes you a HUGE “thank you” for your write up.


After such a thorough write up, once you finish a test grow with this light, @MarsHydro_LED should send you their top of the line grow light for you to do a full review of it…


Great write up @Northern_Loki a lot of it is Chinese to me in understanding certain aspects of it all wish I knew more about lighting maybe someday!


I probably won’t be documenting a test grow myself (just too long of a process to keep track for me) although I believe there may be another OG’er or two that might be considering trying that. Looking forward to it if true. Simply writing this up was tiring enough for me :dizzy_face:

If there are somethings that need clarification or if you have a questions, please feel free. I’ll do my best…


Not so much, documenting the entire grow, more so documenting your results, bud density, crystal production etc…


Definitely an awesome review, very in depth and yeah theres quite a bit I dont quite understand but still awesome to have the info there.


@ganjajuana …not too bad on the specs


Thank you very much for your depth review. :+1::+1::+1:
We will sponsor someone on OG to try out one of our new lights, and we all can see how they works in real grow stage. :blush:


@Northern_Loki Thanks mate, that’s the kind of info the manufacturers should be providing. A pity it had to come from a third party.
I understand now :wink:
@MarsHydro_LED Alot of people here are looking forward to watching the side by side comparison grows. “The proof is in the pudding” as is said.

Overall, it seems that mars hydro is learning, along with the ever learning indoor aficionados. Keen to see how this progresses.


Addressing some of the comments in the “review” would be helpful, too. Thanks.

I, as well.


@Northern_Loki Thank you very much for your time and energy for all research and testing. It’s worthy of taking a look at back and forth. A very detailed and professional infomation on our SP 250. :+1:

But there are few things we want to be cleared.

  1. For our blurple lights, why the light is purple ? Its because a mixed red and blue spectrum will perform a purple light.

There are two buttons for veg :four_leaf_clover: and bloom, turn “growth” or “growth” and :tulip: “bloom” on for veg :four_leaf_clover:, keep both on for flower. :tulip:
Plants needs more light in blue wavelenth for germinationa and veg, more light in red wavelength for flower.
Which the perfect wavelength for blue is 450nm around, for red is 650 around. It’s enough for strians growing and flowering. :wink:

Buying from an agent is the same to buy from our official website, if you are living one of our warehouse located country, the shippment will be very fast been delivered. If you are not living in these country, you can also contact us to ask if we have an agent in your country, if so, we will recommend you their contact info directly.

Where are our warehouse location ?

:checkered_flag: UNITED STATE:
ADD:5650 Grace place City of Commerce CA 90022 USA

New Jersey
ADD: 1000 High Street, Perth Amboy, NJ 08861 USA

:checkered_flag: CANADA:
110-6351 Westminster Highway Richmond

:checkered_flag: UNITED KINGDOM:
DUNSTABLE, LU5 4RZ,United Kingdom

:checkered_flag: GERMANY:
Ginsheimer Str.8
65462 Ginsheim-Gustavsburg, Germany

:checkered_flag: AUSTRALIA:

:checkered_flag: RUSSIA:
No. 67,23 building, Business Park “Greenwood” ,MKAD 69 km

We use the latest version Epistar without lens cover, there are 2 pictures for your reference.

Thanks again for your detailed and professional review [Greatful]