Key takeaways
- The HLG 550 V2 R-Spec, B-Spec and ECO are discontinued. The HLG 600 R-Spec is the direct replacement for the R-Spec and runs the same 5 x 5 ft flower footprint.
- All three 550 models were 480 W fixtures at 2.50 to 2.67 µmol/J. Seven current models beat the best of them.
- The most efficient fixture in the range is the HLG 350 R-Spec at 3.11 µmol/J, which is a 330 W light, not a flagship.
- The ECO was the one 550 with no ETL listing. Most commercial rooms and many insurers need an ETL or UL mark, and that has not changed.
- Quantum board is a Horticulture Lighting Group term. Look-alike boards often skip the safety listing and the third-party lab report.
The HLG 550 V2 is the fixture that made quantum boards mainstream, and it is also the fixture people are still searching for six years later. This is where that line stands now, what each model turned into, and how the current range compares on the numbers that matter.
Growers write the names both ways, so an HLG 550 V2 Rspec review and an HLG 550 review are after the same fixture. The HLG R-Spec series itself now runs from 330 W to 720 W. Everything below is the manufacturer figure as it appears on the fixture it belongs to. Where a model is no longer made, it is marked that way rather than quietly dropped, because the specification is still the reference point most growers are comparing against.
Where the 550 V2 line stands
All three 550 models are out of production. The line was replaced rather than discontinued outright.
The HLG 550 V2 R-Spec and B-Spec gave way to the HLG 600 series, which raised the wattage ceiling and moved onto newer diodes at the same place in the range. The 550 ECO, the cost-first option, is now covered by the HLG 600 QB288 V2 Rspec LED Kit — the same four-board idea sold as a kit.
None of that makes the 550 numbers useless. They are the benchmark a lot of growers still size against, and the sections below put them next to what Horticulture Lighting Group builds today so the comparison is on one page.
The three 550 models, side by side
All three were 480 W four-board fixtures on the same 26 x 20 x 3 inch chassis, dimmable, with 120 V, 208 V, 240 V and 277 V cord options.
| Model | Wattage | µmol/J | Spectrum | Flower footprint | Veg footprint | ETL listed |
|---|---|---|---|---|---|---|
| HLG 550 V2 R-Spec (discontinued) | 480 W | 2.67 | Full-spectrum white plus 660 nm deep red | 4.5 x 4.5 ft or 4 x 5 ft | 6 x 6 ft | Yes |
| HLG 550 V2 B-Spec (discontinued) | 480 W | 2.55 | Full-spectrum white plus 470 nm deep blue | — | 6 x 6 ft | Yes |
| HLG 550 ECO (discontinued) | 480 W | 2.50 | 3K full spectrum or 4K veg | 4 x 5 ft | 6 x 6 ft | No |
The spread between them was small on paper and large in practice. The R-Spec carried 660 nm deep red and was the one light that could run a crop start to finish. The B-Spec leaned on 470 nm blue and was built for mothers and veg, where tight internodes matter more than flower weight. The ECO traded the ETL listing and a little efficiency for a lower price.
Growers often framed the choice as ECO LED vs full LED, and the honest version is that the spectrum was the smaller half of it.
That ETL line was the one that caught people out. Many municipalities and insurers require an ETL or UL mark on electrical equipment in a commercial room, and the ECO never had one. For a home grower it was a judgement call. For a licensed facility it usually ruled the fixture out, and the same logic applies to anything you are comparing today.
What replaced each one
Matching by role rather than by model number is the quickest way across.
The HLG 600 R-Spec is the straight swap for the 550 V2 R-Spec: 1,522 PPF at 2.60 µmol/J from four Samsung LM301H boards with 660 nm deep red, dimmable from 60 W to 600 W on auto-sensing 100–277 V input, passively cooled.
For the B-Spec's job the closer match is the HLG 250 VEG PRO. It is a veg-only fixture that dims 40 W to 240 W, puts out 600 PPF at 2.70 µmol/J across a 5 x 5 ft veg footprint, and carries UL 8800 certification. Half the power of the 550 B-Spec for the same room.
Every current model, compared
Eleven fixtures, from a 65 W single board to a 720 W five-bar, plus the controller that ties the big ones together.
| Model | Wattage | PPF µmol/s | µmol/J | Flower footprint | Veg footprint |
|---|---|---|---|---|---|
| HLG 65 V2 | 65 W | 152 | 2.35 | 2 x 1 ft | 2 x 2 ft |
| HLG 100 V2 | 95 W | — | — | 2 x 2 ft | 3 x 3 ft |
| HLG 250 VEG PRO | 40–240 W | 600 | 2.70 | — | 5 x 5 ft |
| HLG 350 R-Spec | 330 W | 1,011 | 3.11 | 3 x 5 ft | 5 x 5 ft |
| HLG 600 R-Spec | 60–600 W | 1,522 | 2.60 | 5 x 5 ft | 6 x 6 ft |
| HLG 600 QB288 V2 Rspec Kit | 620 W | 1,525 | 2.50 | 5 x 5 ft | — |
| HLG Scorpion Rspec 600W | 60–600 W | 1,584 | 2.62 | 5 x 5 ft | 6 x 6 ft |
| HLG Tomahawk 650 (GrowFlux) | 650 W | 1,920 | 2.94 | 5 x 5 ft | — |
| HLG Tomahawk 720 (GrowFlux) | 720 W | 2,161 | 2.87 | 5 x 5 ft | — |
| HLG Tomahawk 720 (RJ dimming) | 720 W | 2,161 | 2.87 | 5 x 5 ft | 6 x 6 ft |
| HLG 750 Diablo | 715 W | 2,056 | 2.88 | 5 x 5 ft | 6 x 6 ft |
Two naming notes, because the catalogue and the search box disagree. The HLG 600 Rspec and the HLG 600 R-Spec are one fixture, and the 3000 K version of the 100 V2 is listed as the HLG 100 Rspec. A search for 600 Rspec lands on the same light either way.
Several earlier boards still come up often and are no longer in production: the HLG 135 V2 grow light, the HLG 200 Rspec and the HLG 300 Rspec. Match those by footprint against the table above rather than by model number.
The GrowFlux Access Point is the piece that is easy to miss. It is a wireless mesh hub that links up to 200 fixtures and sensors over AetherMesh at around 500 ft indoor range, which is what turns the GrowFlux versions of the Tomahawk into a scheduled, app-dimmed room rather than eleven separate knobs.
What a quantum board actually is
A flat aluminium board carrying a large number of low-power diodes, with no heatsink fins and no fan.
Spreading the load across many diodes running gently is what lets the board shed its heat passively, and losing the heatsink is what makes the fixture thin and light. In a multi-tier rack or a tent with limited headroom, that profile is as much of the appeal as the efficiency.
The design came out of two earlier companies, Johnson Grow Lights and Northern Grow Lights, both building COB replacements for HID fixtures at a point when COB efficiency had flattened out. Their founders combined a new Samsung diode with the flat-board idea and released the QB304 around 2016. Quantum board is their term and their trademark.
What the best quantum boards have in common
HLG grow lights have been built around that same flat plate since 2016, and the brand sits near the top of most best LED grow lights shortlists for one reason: the figures come from an outside lab and the reports are published. That is the test to apply to anything else in the category.
Why the look-alikes are not equivalent
Flat white boards from overseas factories now fill the category, and some of them photograph identically. Two things usually separate them. The first is the safety listing: an ETL or UL mark means the fixture has been tested to fail safely, and copies frequently have neither. The second is the driver.
Most fixtures in this class use MEAN WELL drivers, but MEAN WELL makes a wide range and the entry-level units are not the high-grade ones. The badge on the driver tells you less than people assume, and a cheaper driver costs system efficiency and service life rather than just a few dollars at the outset.
Reading efficiency, and who to believe
Micromoles per joule is how much usable plant light a fixture produces for each joule of electricity it draws.
A 2.60 µmol/J fixture and a 3.11 µmol/J fixture at the same wattage are not close: the second puts almost 20% more light on the canopy for the same meter reading, every hour, for the life of the room. Over a few years that gap is the difference between two fixtures that looked similarly priced.
The number is only worth what the testing behind it is worth. Horticulture Lighting Group sends fixtures to Light Laboratory Inc. in Anaheim, California, an independent lab with no stake in the result, and publishes the reports on the product pages. The 550 V2 R-Spec came back at about 2.67 µmol/J that way.
The same company bought a competing fixture advertised at 2.7 µmol/J and sent it to the same lab. It measured 2.5. That is the whole argument for asking any manufacturer for the report in PDF form before committing to a room full of fixtures, and for treating a refusal as the answer.
Choosing by room, not by model number
Start from the canopy you are lighting and the job the light has to do, then read across the table.
How to land on a fixture
- Measure the canopy, not the room. A 5 x 5 ft fixture over a 4 x 4 ft canopy wastes light on the walls.
- Decide whether the light runs the whole cycle or only veg. A veg-only fixture gets you more coverage per watt because it does not need the red.
- Check whether your room needs an ETL or UL listing before anything else, because that removes options rather than ranking them.
- Compare efficiency last, between the fixtures that already fit. It is the tie-breaker, not the filter.
- If more than a handful of fixtures are going in, price the controller at the same time rather than later.
For a 2 x 2 or 3 x 3 tent
The HLG 100 V2 flowers a 2 x 2 ft space or vegs a 3 x 3, in 3000 K or 4000 K. The HLG 65 V2 is the propagation version of the same board at 65 W and 152 µmol/s.
For a 3 x 5 or small 5 x 5
The HLG 350 R-Spec flowers 3 x 5 ft and vegs 5 x 5 at 330 W, and it is the most efficient fixture in the range at 3.11 µmol/J. Its two Diablo boards are why it is often called the HLG 350R Diablo. For the HLG 350R wattage, its footprint and a full HLG 350 Diablo review, our HLG 350R against the Mars Hydro FC 3000 goes through it properly, and our HLG 225W Elite review covers the smallest Diablo fixture.
For a full 5 x 5
Four fixtures cover it and they are not interchangeable. Each is a 600 watt full spectrum LED grow light in the broad sense, and each puts that light down in a different shape. The HLG Scorpion Rspec 600W is a six-board light at 1,584 µmol/s that hangs about 12 inches off the canopy. The HLG 750 Diablo runs 715 W for 2,056 µmol/s with integrated reflectors at 15 to 24 inches. The Tomahawk 650 and the two Tomahawk 720 versions are five-bar fixtures, which spread light differently from a board. For the 600 R-Spec against a common competitor, see our HLG 600 R-Spec and Spider Farmer SF7000 comparison.
Wireless or a knob
The Tomahawk comes both ways. The GrowFlux version schedules and dims from an app once an Access Point is on the network. The RJ version has a dimming knob and an RJ port and needs nothing else. One room, one or two fixtures: take the knob.
FAQs
The questions that come up most often about this line.
Is the HLG 550 V2 still made?
No. The R-Spec, B-Spec and ECO are all out of production. The HLG 600 R-Spec took the R-Spec's place in the range.
What is the difference between the HLG 550 R-Spec and B-Spec?
Spectrum and nothing else of substance. Both were 480 W on the same chassis. The R-Spec added 660 nm deep red and ran a full cycle; the B-Spec added 470 nm blue and was built for veg and mothers.
Is the HLG 550 Rspec the same light as the HLG 550 V2 R-Spec?
Yes. Rspec and R-Spec are the same model written two ways, and the HLG 550 V2 ECO is the third fixture in the same line.
Was the HLG 550 ECO worth the saving?
It depended entirely on the room. The ECO gave up the ETL listing and a little efficiency. In a licensed facility that usually settled the question on its own, because the listing is a requirement rather than a feature.
How much better is the HLG 600 than the 550 it replaced?
On the published figures the 600 R-Spec runs 1,522 PPF at 2.60 µmol/J against the 550 V2 R-Spec's 2.67, so it is slightly behind per watt but takes more watts and puts considerably more light on the canopy. For a 5 x 5 ft flower footprint that is the trade most growers want.
Which HLG fixture is the most efficient?
The HLG 350 R-Spec at 3.11 µmol/J, which is the smallest of the flowering fixtures rather than the largest.
Are cheaper quantum boards the same thing?
Quantum board is a Horticulture Lighting Group trademark, so a look-alike using the phrase is not using a licensed design. Check for an ETL or UL mark and ask for the third-party lab report before comparing the headline efficiency figures.
The bottom line
The 550 V2 earned its reputation and then got replaced by lights that do the same job better.
The honest caveat is that efficiency has stopped moving as fast as it did between 2016 and 2020. The gap between the 550 V2 R-Spec at 2.67 and the 600 R-Spec at 2.60 is not an improvement at all on that one measure, and the real gains since then have come from output, controls and build rather than from micromoles per joule. A fixture bought today will not be obsolete in two years the way the 2016 generation was.
If you are replacing 550s and want to match the room you already have, send us the canopy dimensions and whether it runs veg, flower or both, and we will work through it with you.