Key takeaways
- Measured from 350 to 800 nanometres, the 600W Ceramic HPS put out 275 watts of radiant energy against 261 watts from a 600W Super HPS — about 5% more, spread far wider.
- The Super HPS spikes to roughly 7 W/nm near 568 nm; the Ceramic HPS never climbs past about 1.15 W/nm, which is exactly why its lumen reading looks so much smaller.
- Lumens weight every wavelength by human eye sensitivity, so across five 600W lamps the lumens-per-micromole figure swings from 55 to 92 — a 67% spread on the same wattage.
- Ceramic HPS runs on electronic ballasts above 100 kHz, not on magnetic core-and-coil gear, and can take up to 20 minutes to reach full white light.
- The 600W system is built around a 4 x 4 footprint at about three feet; start nearer four feet in veg and come down through flower.
Hey everyone, Nate with GrowersHouse here. Ceramic HPS is one of those phrases that stops a grower mid-sentence, because ceramic and high pressure sodium spent twenty years in separate lanes: ceramic metal halide on one side, HPS on the other. Running a ceramic arc tube at 600 watts puts both in the same envelope, and the question everybody asks next is whether the numbers back it up.
I put a 600W Ceramic HPS on the meter next to a 600W Super HPS and read both spectra end to end. What came back is more interesting than the marketing, and it turns on one measurement that almost nobody checks.
What a Ceramic HPS lamp is
A standard high pressure sodium lamp runs its arc inside a translucent alumina tube and produces that familiar amber light. A Ceramic HPS keeps the sodium chemistry but changes what surrounds it, and the result reads as near-white to the eye instead of orange. The 600W version arrives as a lamp with a matched fixture and ballast built around it, which is the part worth paying attention to — the gear was specified for this lamp rather than being something close enough that happened to fit.
Eye Hortilux developed it, and the Eye Hortilux range is where the rest of the brand's lamps sit. The pitch is straightforward: a ceramic-style spectrum with the intensity growers expect from a 600-watt flowering lamp, aimed squarely at people who liked what 315W ceramic did to plant structure but wanted more reach into the canopy.
That last point matters more than it sounds. Growers who moved from a high-intensity HID setup down to 315W ceramic lamps often describe the same thing — the canopy looks better at the top and thinner underneath. A 600-watt ceramic arc is an attempt to keep the spectral character and put the intensity back.
Why the lumen number misleads
Put a 600W Ceramic HPS and a 600W Super HPS side by side on a lux meter and the Ceramic reads dramatically lower. Growers see that gap and conclude the ceramic lamp is weaker. It is the wrong conclusion, and the reason is in how the lumen is defined rather than in either lamp.
A lumen is light weighted by the human eye's sensitivity curve, which peaks around 555 nanometres in the yellow-green and falls away steeply toward blue and deep red. Sodium emits almost all of its energy in a narrow band sitting right under that peak, so a standard HPS scores enormously well on a meter built to measure what people see. A lumen meter is not measuring light the plant can use; it is measuring light a person can see.
The practical size of that distortion is easy to show with published figures. Across the five 600-watt lamps listed further down, dividing initial lumens by photosynthetic photon flux gives anywhere from 55 to 92 lumens per micromole per second. Same wattage, same wall draw, and a 67% swing in how flattering the lumen figure is. Pick by lumens and you are ranking lamps by a yardstick that changes length depending on the spectrum.
What the measurement showed
The honest way to settle it is to stop weighting anything and simply add up the energy. Measured across 350 to 800 nanometres, with no eye-sensitivity curve applied, the two lamps came out like this.
| Lamp | Total radiant energy, 350-800 nm | Tallest peak on the trace |
|---|---|---|
| 600W Super HPS | 261 W | About 7 W/nm near 568 nm |
| 600W Ceramic HPS | 275 W | About 1.15 W/nm |
The Ceramic HPS delivered 14 watts more radiant energy, around 5% ahead, while its tallest spectral peak is roughly a sixth the height of the Super HPS peak. That pair of facts is the whole argument. One lamp concentrates its output into a few towering spikes; the other spreads a similar total across the band. A meter that rewards spikes under the eye's sensitivity peak will always flatter the first.
Worth saying plainly: these are watts of radiant energy, not micromoles. The two are related but not interchangeable, and a lamp with more radiant energy is not automatically ahead on photon count. What the measurement rules out is the idea that the Ceramic HPS is a dimmer lamp. It is not. It is a differently shaped one. The same effect shows up when you run a single HPS lamp across a range of wattages and watch which parts of the trace move.
Where the energy sits
Read the Ceramic HPS trace on its own and the shape makes sense. Relative output climbs gently through the blue, puts a sharp spike near 500 nm, reaches about 90% of maximum around 565 nm, then drops into a deep notch close to 590 nm before jumping to its full peak at roughly 625 nm.
That notch is characteristic of a high pressure sodium arc: the cooler sodium vapour at the edge of the arc reabsorbs the very wavelength the hot core emits most strongly. The Super HPS shows the same notch, which is the narrow downward spike splitting its tallest peak in two.
Past 625 nm the Ceramic HPS stays high, holding somewhere near 57% of its peak all the way out to 740 nm. A standard HPS has collapsed to a fraction of that by 700. The red tail is where the extra 14 watts largely lives, and it is also why the lamp looks white rather than amber — there is enough energy spread either side of the sodium lines for the eye to stop reading it as orange. At 2500K it still sits firmly on the flowering end of the Kelvin scale.
Ballast and warm-up
Two operating details catch people out, and both come straight from the manufacturer's own documentation rather than from field lore.
The lamp runs on electronic ballasts operating above 100 kHz and must not be put on magnetic core-and-coil gear. That rules out a lot of older HID equipment sitting in sheds. If the ballast in question is a traditional transformer-and-capacitor unit, this lamp is not the upgrade path — the starting behaviour of a ceramic arc is a different problem from the one those ballasts were built to solve, which is the same reason probe-start and pulse-start metal halide lamps are not interchangeable either.
The second detail is warm-up. Hortilux states the lamp can take up to 20 minutes to produce white light and reach full power. On a first run that is unnerving, because what you see for the first few minutes looks nothing like the finished colour. It is normal. Take any meter reading before the lamp has settled and the number is meaningless.
Replacement follows the usual HID pattern rather than anything exotic. The manufacturer's guidance puts optimal growth at eight to nine months on a twelve-hour photoperiod, which lines up with how lamp output falls away long before a bulb fails. Burning position is horizontal within about 15 degrees.
Footprint and hang height
The 600W fixture is laid out for a four-by-four-foot area with the lamp hanging about three feet above the canopy. Measured dimensions are 12.7 inches wide, 23.6 inches long and 7.1 inches tall, not counting whatever hanging hardware adds on top.
Three feet is a starting point, not a setting. Young plants going into veg are happier nearer four feet, or a little higher if they are stretching for other reasons. As flowering begins you can bring the lamp down toward three feet, and late in flower a bit lower still once the plants have acclimated. Move it in increments and watch the top of the canopy rather than trusting a number.
If the room is wider than 4 x 4, the answer is more fixtures with overlapping cones rather than one lamp hung higher. Raising a single lamp to cover more floor trades intensity for area at roughly the square of the distance, and the edges still come out dim. A complete double-ended unit such as the Iluminar IL DE 750/600W fixture arrives with lamp and ballast together and switches between the two wattages, which is a tidy way to add a second position without assembling it piece by piece.
Veg, flower, start to finish
Hortilux publishes a growth-power chart for the lamp, and it is honest about where the strength is. Flowering scores at the top of the scale, start-to-finish just behind it, and vegetative growth lands partway along — good, not best.
That matches the spectrum. A 2500K lamp with its peak in the red is doing flowering work, and the blue it carries is enough to keep structure tight rather than enough to run a veg room on its own. Growers who want a single lamp for a whole cycle can absolutely run it start to finish; growers with separate veg space will get more out of a metal halide there and save the ceramic for flower.
For a small veg footprint, something like the Eye Hortilux MH 250W E-Start bulb at 4250K and 21,500 lumens covers the blue-heavy end at a sensible wattage.
The 600W lamps compared
Here is the 600-watt field as it currently stands, with published photosynthetic photon flux alongside published lumens so the gap between the two is visible rather than theoretical.
| Lamp | Type | Colour temperature | PPF | Initial lumens | Rated life |
|---|---|---|---|---|---|
| Growers Choice DE 600W HPS 2K | Double-ended HPS | 2000K | 1050 µmol/s | 90,000 | 15,000 h |
| Ushio HiLUX GRO 600W MH DE | Double-ended MH | 5500K | 1040 µmol/s | Not published | 6,000 h |
| GrowLite Real Red 600W HPS | Single-ended HPS, E39 mogul | 2000K | 954 µmol/s | 88,115 | 32,000 h |
| Growers Choice DE 600W MH 4K | Double-ended MH | 4000K | 800 µmol/s | 60,000 | 6,000 h |
| Growers Choice DE 600W MH 10K | Double-ended MH, finishing | 10,000K | 650 µmol/s | 36,000 | 6,000 h |
Run the arithmetic and the point from earlier lands hard. The 10K finishing lamp reads 36,000 lumens against the HPS lamp's 90,000 — on a meter it looks like 40% of the light. In photon terms it is 62%. Lumens per micromole runs from 55 on the 10K lamp to 92 on the single-ended Real Red, which means a lumen comparison between those two is wrong by a factor of 1.7 before anyone has made a decision.
Two other things in that table are worth a second look. The single-ended Real Red is rated for 32,000 hours against 15,000 for the double-ended HPS, which flips the usual assumption that double-ended is simply better; it reaches a lower peak and holds it for twice as long. And both metal halide lamps are rated at 6,000 hours, which is normal for MH and a reason to plan replacement by calendar rather than by whether the lamp still lights. The rest of the double-ended range runs up to 1000W for anyone sizing past a single 4 x 4.
Which one to run
The 600-watt class exists for a specific room: a 4 x 4 that wants real HID intensity without the heat and the ceiling height a 1000W double-ended setup asks for. Inside that bracket the decision splits three ways.
If the room is a flowering room and the ballast is electronic, HPS at 2000K is still the highest photon count on the list, and the Growers Choice double-ended lamp in the table above leads it. If the gear is older single-ended equipment with a mogul socket, the Real Red covers the same colour temperature with a much longer service life. If the room runs veg or needs a cooler spectrum, the metal halide lamps carry the blue, with the 10K reserved for the last couple of weeks rather than used as a main lamp.
If the appeal of ceramic was the spectral quality rather than the wattage, the 315W ceramic metal halide range is the nearer relative, and we have PAR-tested ten of those lamps against each other if you want the measured ranking rather than the brochure. Stepping up instead of sideways, the 1000W HPS comparison covers the next class, and our 600-watt picks put the HID and LED options side by side if the decision is still open between technologies.
Frequently Asked Questions
The questions that come up most often about Ceramic HPS, answered without the hedging.
Is Ceramic HPS the same as CMH?
No. Ceramic metal halide runs a metal halide chemistry inside a ceramic arc tube. Ceramic HPS keeps sodium chemistry. They look similar on a shelf and behave differently in a room, and the common CMH questions are worth reading if you are weighing the two.
Will it run on my existing 600W ballast?
Only if that ballast is electronic and switching above 100 kHz. Magnetic core-and-coil ballasts are explicitly excluded by the manufacturer.
Why does it look wrong when it first strikes?
Give it 20 minutes. Full white light and full power both arrive late on a ceramic arc, and the colour during warm-up tells you nothing about the finished output.
How does 600W compare with 315W ceramic?
Roughly double the wattage and considerably more penetration into the canopy. Growers who moved down to 315W from higher-intensity HID frequently report the lower half of the plant filling in less, which is the gap a 600-watt ceramic arc is aimed at.
Should I compare lamps on lumens or micromoles?
Micromoles, every time. The table above shows the same five lamps ranking differently depending on which number you read, and lumens is the one weighted by human vision rather than by photosynthesis. The same rule applies when comparing HPS against LED.
How often should the lamp be replaced?
Eight to nine months at twelve hours a day, per the manufacturer's own guidance. Output falls steadily well before the lamp stops striking, so replacing on a schedule beats replacing on failure.
The Bottom Line
A Ceramic HPS is not a brighter lamp than a Super HPS, and it is not a dimmer one. It is a wider one. Measured across 350 to 800 nanometres it carried 275 watts of radiant energy against 261, with a peak roughly a sixth the height, and that single difference explains every confusing lumen reading a grower has ever taken off one.
The practical consequence is simple enough to act on. Compare lamps on photosynthetic photon flux, not on lumens, because the lumen is weighted by human vision and swings by 67% across the same five 600-watt lamps. Check that the ballast is electronic before anything else. Give the lamp its twenty minutes before trusting a meter. And size the room around a 4 x 4 at roughly three feet rather than hanging one lamp higher and hoping.
If you are sizing a 600-watt room and want a second opinion before committing, give us a call or leave a comment below — we would rather talk it through than have you find out after the first flower run.
Happy growing,
Nate