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Best Grow Light On The Planet? You Decide.

Video Face-Off: Review and PAR Testing--Grow Light Science GROW 300 vs. Mars Hydro SP 3000

In this post, we present our recent video face-off between our GROW 300 and the Mars Hydro SP 3000. We review and PAR test each fixture, calculate the price per unit of light output, and see how they measure up on a head-to-head basis. It is expected to be the first in a series of product reviews where we test and evaluate Grow Light Science grow lights and popular competitive products.

Following the video, we have included a written report of our findings.


The grow light decision-making process is complicated. Many factors enter into the equation when you are considering which is the best grow light on the planet for your particular cultivation application. These typically include:

· Source—LED, HPS, CMH, others

· Spectrum

· Componentry

· Light Output - PPF (Photosynthetic Photon Flux)

· PAR Distribution—PPFD uniformity, veg and flowering footprints

· Fixture Size/Shape

· Warranty Length

· Brand Reputation

· Service and Support

· Customer Reviews

· Price

All of these are important considerations, of course. However, one often overlooked metric is the among the most important of all, in our view. The very first thing you ought to ask yourself is, how much flux will I get for my bucks? In other words, what is the price per unit of light output?

It is a simple calculation to make really. Just divide the price of the grow light by the amount of light it produces.

Price Per Unit Of Light Output = Fixture Price

PPF (umol/s)

Try it. You may be surprised to learn that prices per unit of LED light output vary widely--from as low as $0.47 (Grow Light Science GROW 300 and GROW 200) to well over $1.00.

Photosynthesis occurs when photons of certain wavelengths reach plant chloroplasts and trigger a series of chemical reactions. It doesn’t matter to your plants how those photons are produced. So, if you assume all other things (e.g. spectrum, warranty, componentry) happen to be equal, why not get the most photons for your money? Why not BEGIN your decision-making process by answering this key question?

At Grow Light Science, we strongly encourage the comparison of all of grow lighting options on this basis.

PAR Test and Review: Grow Light Science GROW 300 vs. Mars Hydro SP 3000


The GROW 300 is an exceptional LED grow light for home and smaller scale commercial operations. It’s been very well received since introduced in late 2019. And we just released an updated version of the light in November 2020.

At 46” long x 12” wide, the GROW 300 can be operated individually or arrayed in multiple configurations depending on your space and canopy dimensions. Two of them together will flower a 5 x 5 area.

The GROW 300 has 1,056 diodes including Samsung whites and OSRAM 660 nm reds. The OSRAM reds are the recently released OSLON Square, Hyper Red Gen 3 LEDs. These amazing chips deliver an industry-best 4.42 umol/j and they are the heart and soul of our Grow Light Science HI RED spectrum. They are also one of the keys to our exceptionally higher efficacy levels.

Recent updates to the GROW 300 include a power increase to 321 W, an increase in light intensity to 884 umol/s of total PPF, and 813 umol/s of usable PPF. (The difference between these two metrics will be explained next.) At the list price of $419.00, and total PPF of 884, the price per unit of light output for the 300 is an industry-leading $0.47.


Our test setup is 2 feet by 4 feet, a 0.74 square meter area. It has reflective walls and a non-reflective floor to simulate plant canopy. This test method tells us “usable PPF”, the metric referenced earlier. It’s a real-world way of measuring performance. “Total PPF”, on the other hand, is measured in a lab using an integrating sphere, which captures and measures the total photon flux produced by the grow light.

Since an integrating sphere measures all of the emitted photons, it is always going to be a higher number than “usable PPF”. Usable PPF is a measurement of the photons that actually reach the plant canopy.

The fixture hang height is 20 inches. We chose this height because it allowed both lights (GROW 300 and SP 3000) to deliver PPFD levels in the neighborhood of 1000—ideal for flowering.

After powering on the GROW 300 and allowing it to warm up and stabilize for 30 minutes, we measured the power draw for the GROW 300 at 312 watts. Next we took 32 PPFD readings across our grid using an Apogee quantum meter.

(PPFD stands for Photosynthetic Photon Flux Density. It is a measure of the amount of PAR light, or photosynthetically active radiation, that actually reaches the surface of the plant’s leaves. The unit of measure for PPFD is umol/m2/s. In other words, it is the number of photons that hit a one square meter area in the span of one second.)


After tabulating our readings, this is the PAR map that we get for the GROW 300.

These are terrific results. All readings are greater than 1000 and there is very good uniformity. Adding up each of the readings and dividing by 32, gives us an average PPFD of 1100.

Here are the price and performance metrics for the GROW 300.


When Mars Hydro introduced the SP 3000 in June of 2020, we were a little concerned about it from a competitive standpoint, and we wondered how it would measure up against our GROW 300. At their $400 price point and advertised output level, the price per unit of light for the SP3000 would be around 48 cents/PPF – very close to the GROW 300s price of 47 cents.

It appears to be a nicely designed, high performance grow light. Dr MJ Coco reviewed it shortly after its release and he said it was one the most impressive grow lights he had ever reviewed.

· At 42.5” x 3.2”, it can be run individually or arranged in multiple array configurations

· The light has 960 LEDs including Samsung and OSRAM 660 nm chips

· It has good spectrum and good componentry. Although, upon close examination, Mars is not using the latest OSRAM red LEDs. This is not a surprise since many manufacturers have yet to upgrade to the latest generation red diodes as we have at Grow Light Science.

With respect to performance, Mars Hydro advertises the following:

· 300 watts of input power

· An exceptional level of PAR efficacy at 2.8 umols/j

· Total PPF is not referenced but, if efficacy is 2.8, then we can multiply that by their 300 watts of input power to get a PPF of 840 umols/s…seems reasonable.

· “Usable PPF” is not reference either, but we will measure it here.


As with the GROW 300, we set our hang height at 20 inches.

Next we checked the power draw for the SP3000. Surprisingly, it was drawing just 266 watts of AC input power, well below the 300 watts listed by Mars Hydro for this light. So how could this be, we wondered? We verified that the dimming control was at 100%, so that was not the reason.

We took a look at the power specs listed on the driver and found the explanation. It shows that for input voltages higher than 200, the maximum output power is 301 watts. However, for the input voltage range of 100 to 200 volts, the maximum DC output power is only 256 watts. Since we are powering each of our lights in this test using a common 120V outlet, the SP3000 driver is reducing the power output accordingly.

Bottom line is that the SP3000 is NOT a 300 watt light at common North American voltage levels. And it was not going to put out 840 umol/s of PPF, as we just estimated.

Next we took PAR readings for the SP 3000 to see how it actually performs.


Here is the PAR map that we get for the SP3000.

Readings range from 765 up to 927. The average PPFD is 856 umol/m2/s. A little on the low end but still good for flowering. The light could be lowered some to increase intensity, but uniformity would suffer as readings in the corners and edges drop off.

Here are the price and performance metrics for the SP 3000.

· Usable PPF is 634 umol/s, well below the 840 we had estimated for total PPF based on Mars Hydro’s advertised specs

· Usable Efficacy is 2.38 umol/j

· And, the price per usable PPF is coming in at $0.63


The GROW 300 and the SP 3000 are very comparable LED grow lights in terms of price point, size, and advertised performance. But head-to-head testing, and a comparison of the results, tells a different story.

Here’s how they stack-up.

The GROW 300 beats the SP 3000 in every key metric based on our head-to head PAR testing in identical setups—greater intensity, more power, and superior efficacy. The 300’s higher average PPFD means it delivers more light to your plant canopy. And most importantly, the bottom line our view, a considerably lower price per unit of light output—in fact, almost 20% lower.

Our mission here at Grow Light Science is to design and manufacture grow lights that offer the highest quality spectrum and efficacy, at the lowest possible price—the most photosynthetic photon flux for your bucks—we like to say.

And we have done that with the GROW 300. Customer satisfaction and reported yields continue to be outstanding.

We strongly encourage the comparison of grow lights on this basis—ask yourself, how much light will I actually be getting for the price? And, if you can find a better light for your money, buy it!

Happy growing!

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