We can only take credit for our effort. Best practices, equipment, process, recipe… these things all come from elsewhere and wisdom should be accumulated through experience as well as knowledge. That’s internal + external. Well unfortunately, not every experiment finishes with a definite answer or obvious outcome. This is one of those cases. We were hoping for an obvious margin here, something to definitively state ‘Light A is superior to Lights B, C and D. But that turned out not to be the case. We are left with more questions than answers. At the risk of providing more annoyance than confidence; read on at your own risk.

Gavita 1700e vs Flexstar vs Phantom Photobio vs Mars Hydro

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At Montana Cannabis Company, we try to make fine adjustments every harvest in the attempt to keep moving the needle towards that elusive perfect run. We have a lot of help from our vendors, technology partners, nutrient companies and network of master growers/breeders/cultivation techs and cannabis hobbyists. The reason we write up our findings is to add to the body of knowledge. We think of it as ‘Passing The Fire’ to the next generation of growers, just like those who came before us did for our (and our customers) benefit.

It’s thrilling to be in a position to run a multiple light ‘grow off’. It seems only yesterday we were fretting over cost and quality to build out our very first grow tent and decide on which light fixture to begin this cannabis journey. Now, we’ve amassed nearly 50 lights that are in constant use at our primary facility and collected a handful more that we’re able to use in our mother room, over our vegging clones and now for the first time; flowering our plants side by side to compare results.

Before we dive into the details, we have to quickly introduce some starting points if you want to see where we’ve come from.

Previous experiments include:

Now onto the light comparison. We have in no particular order…

GAVITA 1700e





Each light was assigned to x5 cannabis clones of the same strain, from the same mother who were each the same rooting age and had been fed, lollipopped/defoliated in identical manners to ensure an equal starting point. We began our 2 week veg with the lights 18" over the top of the uniform canopy taking úmol readings every light intensity ramp up/down.

Each light was gradually ramped up from 70% power to 100% and allowed to maintain 100% intensity for the majority of our 68 day flower period. That’s a bit long for this strain as I’d typically say ‘Rare Backdoor Candy (Rainbow Chip x Bonkers x Froyo) matures to harvest in 60–63 days. Lights were all backed off to 80% and then 75% for the last two weeks and each plant was flushed for 10 days prior to harvest. We find our flush brings out the colors in the bud as the plant starves itself and gives a better jar appeal, not to mention a smoother dry/cure and improved final product ← — — — Yes I know the jury is still out on this… maybe a follow up experiment?

Rare Backdoor Candy by Montana Cannabis Company

Now to be fair, we didn’t seclude or isolate these plants to be sure they only received light from their intended fixtures. The room was open so you’ll have to take this with a grain of salt but it’s the best we could do in our facility at the moment. I think the results are interesting and valuable none-the-less.


Well, we had a major surprise at the end so I guess I have to put a big asterisk on the results. I’ve grown this strain of R.B.C. many times under our Gavita lights so I may have fudged the experiment by including that control group on a different table/water schedule than the rest of the lights. When we did our chop, I immediately noticed a weight difference and our measurements showed a significant variable between table 1 (Gavitas) and table 3 (Mars Hydro/Phantom Photobio/Flexstar). This can potentially be explained by the different watering times/amounts and even though we try and stay consistent with all watering schedules, different tables/zones require different feed so there’s no doubt some mid-harvest adjustments that may account for our findings. But I was surprised none-the-less and have a bit of a head scratcher explaining the massive wet weight difference.

VISUALS: Cutting to the chase, our Gavita plants looked the least ‘ripe’ followed by the Flexstar and the Phantom Photobio plants looked the most ripe with Mars Hydro in a near second. Under the microscope, we didn’t see any notable difference to add. No additional trichome coverage, size or anything else of note. I did comment in the video at first glance that the Photobio plants appeared more frosty but that may have been due to the leave color contrasting with the white trichomes to make them pop more to the naked eye.

The Mars Hydro plants had some minor to moderate fox tailing although they were in the corner of the room so that may be due to some lower airflow and/or increased heat. Again, I fall upon my sword in cow tow that we couldn’t omit all these variables.

Gavita and Flexstar had minor color changes in the leaves with our colder night temperatures likely being the cause. Healthy green and faded purple from the cold. Mars Hydro and Phantom batches each showed noticeably more oranges/reds and other color distinctions in the flower I typically associate with finished plants, hungry from the flushed water-only diet.

TRICHOME COVERAGE: I better be careful here if I can’t back this up scientifically but from the naked eye it did appear that the plants under the Phantom Photobio were the winner. Microscope check didn’t back this up or negate it.

WET WEIGHT: As soon as we got the Flexstar plants out from the netting it was obvious there was a significant increase in wet plant weight. I can’t explain this but the difference nearly warrants a redo test to see if we can replicate the results. This would be a massive find. HYPOTHESIS: The Flexstar light spectrum has more blue frequency and thus promoted better growth during the two weeks of veg allotting for the 9% weight increase.


GAVITA 1700e Pros:

  • Dimmable to 50% power
  • High úmol output
  • Low Amperage per fixture = more fixtures on a breaker line
  • We’ve had fantastic results with them for 3 years


  • The most expensive fixture on our list
  • Annoying light adapters and cord length make hanging and adjusting cumbersome
  • Sharp edges to bump your head on (we’ve all done it!)

Phantom Photobio Pros

  • Very cool light with obviously more red diodes than any other on our list
  • On unit adjustable dim
  • More trichome coverage?
  • This was a free unit for MCC, gifted by a rad grower and hydro shop owner in Bozeman Montana (thanks James!)


  • Heavy
  • Unit takes more wattage and gives off significantly more heat than the other fixtures

Mars Hydro FC6500 Pros:

  • On unit adjustable dim with total analog control of output
  • Plants appears more ‘ripe’ at harvest
  • This unit was freely gifted to us from Mars Hydro (Thanks Kathy!)


  • Was the only light that had our plants foxtailing.

Flexstar Pros:

  • Lightweight and easy to hang
  • Sleek/beautiful design
  • Affordable model
  • Provided the heaviest wet weight plants at harvest by at least 9%


  • Plants didn’t appear ‘ripe’ on harvest day (less jar appeal)
Zach under the Mars Hydro and Phantom Photobio LED light fixtures

Again, apologies must be made for providing more questions than answers on this run but that’s life sometimes. We have grown 3 years worth of premium cannabis with our Gavita 1700e LED’s and continue to be happy with them. However, they were very expensive in comparison to other professional grow lights on the market so we’ve alway kept an open mind on the technology and equipment.

LED’s are great in that they cut down electricity use and byproduct heat and can grow a top shelf indoor product. There’s a lot to take into account when growing great marijuana and lighting is one of the cornerstone decisions you’ll have to make. My ultimate advice is to find a grower you admire (or a friendly local hydro shop homie) and pick their brain on which path to take.

Happy growing. Follow us on instagram @Montana_Canna_Co