Pairs well with
The Plantmax 315W Ceramic Metal Halide (CMH) Lamp puts out a true full-spectrum 3000K bloom-tuned light with a CRI of 92 — closer to natural sunlight than any HPS or standard MH bulb. Built around a ceramic arc tube with double-jacketed glass, this lamp delivers the wide spectrum plants need to drive resin, terpene and essential oil production while running at a fraction of the wattage of a 600W or 1000W HID. Designed for growers who want medical-grade output without the heat or power bill of bigger systems.
Specifications
- This lamp uses a PGZ18/P two-pin socket — completely different from E40 mogul. It needs either a CMH-specific 315W reflector or a PGZ18-to-E40 socket converter.
- Requires a CMH-specific 315W ballast — most are square-wave low-frequency units. Standard HPS or MH ballasts won't run this lamp correctly.
- Common compatible kits include Hi-Par Sunstorm, Adjust-A-Wing Hellion, Nanolux, and similar CMH systems.
- Always handle with clean gloves or a soft cloth. Skin oils on the quartz cause hot spots and shorten lamp life.
- Hot restrike takes 5–10 minutes. Don't try to re-ignite a hot lamp before then.
- The arc tube contains sodium and mercury — dispose of according to local council regulations.
How To Use
Pairs Well With
Browse CMH-specific 315W ballasts — required to fire this lamp. HPS and MH ballasts won't work.
CMH ReflectorsCMH-specific reflectors with PGZ18 sockets — Hi-Par Sunstorm, Adjust-A-Wing Hellion, and similar.
Inline Exhaust FansCMH runs cooler than 600W HID but still pumps out heat — pair with extraction sized for your space.
Rope Ratchets by Cultiv8Hang the reflector at the right height and adjust easily as your canopy stretches into bloom.
Frequently Asked Questions
What is CMH and why is it different from HPS or MH?
Ceramic Metal Halide (CMH) uses a ceramic arc tube instead of quartz — burning hotter and producing a fuller, broader spectrum closer to natural sunlight. HPS skews red-orange and is bloom-only. Standard MH skews blue and is veg-only. CMH covers the full range with a CRI of 92, making it the closest grow-lamp option to actual sunlight.
Will this lamp run on my existing HPS or MH ballast?
No. CMH 315W lamps require a CMH-specific 315W ballast — typically a square-wave low-frequency unit. Running this lamp on an HPS or standard MH ballast won't work and may damage either component. If you're moving from HPS or MH to CMH, you'll need a new ballast.
Can I use this on an E40 reflector?
Yes, with a PGZ18-to-E40 socket converter. The lamp itself uses a PGZ18/P two-pin base which doesn't fit E40 mogul sockets directly. A converter screws into your existing E40 socket and accepts the PGZ18 lamp — useful if you're upgrading from HPS or MH to CMH and want to keep your reflector. Converters are sold separately.
Should I get the 3K or 4K version?
If you're running a single CMH lamp through the full cycle, the 3000K (3K) is the better choice. Plants spend most of their time in flowering, and the warmer spectrum drives bloom while still containing enough blue and UV to support veg. The 4000K (4K) is veg-leaning and best as a dedicated grow-stage lamp in a two-lamp setup.
What size space does a 315W CMH cover?
A single 315W CMH covers a 1.0m x 1.0m flowering footprint or up to 1.2m x 1.2m for veg or supplemental use. For larger spaces, run two 315W CMH lamps or step up to a 630W dual-lamp system.
How does CMH compare to LED or HPS for yield?
CMH sits between LED and HPS for raw yield but typically beats both for spectrum quality and resin/terpene production. A 315W CMH produces yields comparable to a 600W HPS at roughly half the wattage, with better essential oil profiles. Modern LEDs match or exceed CMH on raw efficiency, but CMH still holds an edge for full-spectrum natural light quality.
How long does this lamp last?
Rated 20,000 hours of operation, with 90% lumen and PPF maintenance at 7,500 hours. Most growers replace CMH lamps after 18 to 24 months of regular cycle use to maintain peak spectrum quality.
Does it come with a warranty?
Yes. Plantmax backs every lamp with a one-year limited warranty against defects. Keep your packaging and proof of purchase in case you need to make a claim.
Do you ship Australia-wide?
Yes — we ship across Australia from our Tasmanian base. Free shipping kicks in over $499*. CMH lamps are packed carefully to handle transit, but if anything arrives damaged, give us a yell and we'll sort it.
Sunlight-Quality Spectrum. Half the Wattage.
CRI 92 full spectrum, 3000K bloom-tuned — medical-grade output for serious indoor growers.