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Growers Choice 315W Ceramic Metal Halide CMH Lamp 3100k
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$83.80
Growers Choice 315W CMH 3100K, a warm single-ended bloom lamp
This is the warm lamp in the Grower's Choice single-ended line, part CMH-315W/931/PGZX18/HO, SKU GC315W3K01. It is rated at 570 µmol/s and 37,000 lumens after 100 hours, which works out to 120 lm/W. Colour rendering is CRI 90 or better.
Purchase directly from Growers HouseGrowers Choice 315W CMH 3100K, a warm single-ended bloom lamp
This is the warm lamp in the Grower's Choice single-ended line, part CMH-315W/931/PGZX18/HO, SKU GC315W3K01. It is rated at 570 µmol/s and 37,000 lumens after 100 hours, which works out to 120 lm/W. Colour rendering is CRI 90 or better. Rated life is 15,000 hours on ten-hour starts. It runs at 100V and 3.15A on a C182/O-rated or electronic ballast, with a 198V minimum open-circuit voltage. The base is PGZX18, the standard socket in single-ended 315W CMH reflectors. It is rated for open or enclosed fixtures and for any burning position. Maximum base temperature is 250°C and the bulb itself tops out at 350°C. A phosphor coating on the outside of the arc tube shapes its spectrum. That coating is what pushes output toward the warm end.
Running This 315W CMH Bulb in a Flower Room
What it does well is high photon output in a warm, flower-friendly spectrum. At this colour temperature it sits in the bloom and transitional range and can still carry a veg room in a pinch. In a 4x4 tent, most growers start one lamp around 18 to 24 inches above the tops and come down after the stretch. Pair it with a low-frequency CMH ballast, since standard HPS and MH ballasts will not drive it. A red-enhanced 3K-R version exists in the same range for rooms that want more deep red late in flower. The cooler 4200K lamp from the same line is the better pick for dedicated veg. It is sold as a bare lamp, so the reflector, socket and ballast come separately.
Key Features
570 µmol/s Photon Flux: A PPF figure lets you plan canopy intensity instead of guessing from lumens.
37,000 Lumens at 120 lm/W: High efficacy means more light per watt and less heat for the same output.
3100K Bloom Spectrum, CRI 90+: Warm, broad output supports flowering and keeps plants easy to read under the lamp.
15,000-Hour Rated Life: Rated at ten-hour starts, it covers years of flower cycles before replacement.
PGZX18, Any Burn Position: Fits standard single-ended 315W reflectors, open or enclosed, in any orientation.
Technical Specifications
Specification
Value
Part Number / SKU
CMH-315W/931/PGZX18/HO / GC315W3K01
Lamp Type
Ceramic metal halide (CMH/LEC), single-ended
Wattage
315W
Color Temperature
3100K
Growth Phase
Bloom / transitional
Lumens @ 100 hrs
37,000
Efficacy
120 lm/W
CRI
≥90
PPF
570 µmol/s
Rated Life
15,000 hours (10-hour starts)
Base
PGZX18
Lamp Voltage / Current
100V / 3.15A
Min. Open Circuit Voltage
198V RMS
Ballast
C182/O or electronic CMH
Burning Position
Universal
Luminaire
Open or enclosed
Max. Base / Bulb Temperature
250°C / 350°C






