Metal halide (MH) lamps are a type of high-intensity discharge (HID) lamp. MH grow light produces light through an electric arc and a mixture of gaseous mercury and metal halides. MH bulbs are used for veg, also known as the vegetative stage because this technology puts off a cool blue wavelength, which is why it is best for vegging. This type of light forces bulbs to build thick, sturdy stalks, and robust, leafy foliage.
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Q: Why do metal halide bulbs have a prolonged warm-up period?
A: Metal halide (MH) bulbs exhibit a delayed warm-up period before reaching their full light output. This is noticeable in settings like evening baseball games, where MH lamps are turned on before it gets completely dark. The reason for this warm-up delay is that MH lamps require time, typically 1 to 15 minutes, to achieve 90% of their maximum light output. This initial period is referred to as the warm-up or run-up time.
Additionally, when an MH lamp has been turned off and then needs to be restarted, it cannot be immediately relit. Before it can be restarted, the lamp's arc tube must cool down, or else it will not reignite. This cooling-down phase is known as the restrike time. Traditional probe-start MH lamps can have restrike times of 15 minutes or longer. However, pulse-start MH lamps generally have much shorter restrike times, often more than twice as fast as probe-start MH lamps.
Q: How long is the lifespan of different types of grow light bulbs?
A: The lifespan of grow light bulbs varies depending on factors like their chemical composition and colour spectrum. Here's an overview of the lifespans of different types of grow light bulbs:
HPS (High-Pressure Sodium) Grow Light:
- Lifespan: HPS bulbs degrade at a slower rate compared to MH bulbs and can last approximately 24,000 hours.
- Replacement Frequency: Typically, HPS bulbs need replacement every 10 to 14 months.
- Performance Degradation: They may begin to lose their blue spectrum output first as they degrade.
MH (Metal Halide) Grow Light:
- Lifespan: MH bulbs have a shorter lifespan and tend to depreciate more rapidly than HPS bulbs, lasting about 20,000 hours.
- Replacement Frequency: MH bulbs usually require replacement every 6 to 10 months.
- Performance Degradation: They depreciate faster compared to HPS bulbs.
These lifespans and replacement frequencies are general guidelines and can vary based on specific bulb brands, usage conditions, and other factors. It's essential for growers to monitor their bulbs' performance and replace them when they no longer provide adequate light for plant growth.