GrowLite Tru Blue MH Lamp 6500K | Open Rated Metal Halide, 400W or 600W – 400 Watts

A GrowLite Tru Blue MH Lamp for Tight, Compact Veg Tru Blue is the GrowLite metal halide lamp that runs on the blue end of the spectrum for the vegetative stage. At 6500K it reads as cool daylight, the colour range that keeps stems short and internodes close. That makes it a lamp for clones, young plants and mothers rather than for flower. The bulb is a BT37 envelope on a mogul (E39) base, about 8 in long. It is open rated, so it can run in an open reflector without a glass lens. The 600 watt lamp puts out 40,990 lumens with a colour rendering index of 73. Rated life on that size is 12,000 hours, which covers several veg cycles at 18 hours a day. The higher CRI also makes leaf colour easy to read when scouting for deficiencies or pests. It is single-ended, it is not dimmable, and it needs a ballast of matching wattage set for metal halide. The 400 watt version shares the same 6500K spectrum and base for smaller veg spaces. Running a 600 Watt Metal Halide in the Veg Room A 600 watt metal halide lamp of this kind usually hangs over a veg table or a mother room, where compact growth matters more than speed. Start with the reflector well above fresh clones and bring it down as the canopy thickens and the leaves harden off. Most growers run it 18 hours on and 6 off, then move plants to a warmer bloom lamp at flip. Let the bulb cool before touching it, and handle the glass with gloves or a clean cloth. Metal halide output fades with age, and the blue end goes first. Mark the install date on the reflector so the lamp is swapped on schedule rather than when the plants start to stretch. Heat is real at this wattage, so a tent needs exhaust sized for it, and a sealed room needs cooling. The open rating saves a lens, but the hot glass still needs space from anything that can burn. Run it only on a ballast built for metal halide, because a sodium-only ballast will not drive it correctly. Kept to its schedule, it gives dense, stocky plants that enter flower with short gaps between branches. Key Features 6500K vegetative spectrum: Cool daylight colour keeps stems short and internodes tight. Open rated: Runs in open reflectors without a protective glass lens. Standard mogul base: Threads into any E39 socket on a matching metal halide fixture. 40,990 lumens at 600 watts: Plenty of light to drive a full veg canopy. 12,000 hour rated life: Covers several veg runs before replacement is due. 400 or 600 watts: Two sizes to match the ballast and the space already in place. Technical Specifications Specification Value Brand GrowLite Series Tru Blue Lamp type Metal halide (HID), single-ended Colour temperature 6500K Growth phase Vegetative Wattage 400W or 600W Lumens (600W) 40,990 lm Rated life (600W) 12,000 hours CRI (600W) 73 Bulb shape BT37 Base Mogul (E39) Length 8 in Rating Open rated Dimmable No Part numbers GGL-400-MH-65K, GGL-600-MH-65K