The double ended HPS technology has been making headlines by producing most evident plant growth as compared to other alternatives. It is a unique lamp technology that has paved a new path for horticulturists for better quality and yields. Double ended grow lights have a positive impact on all plants these are installed around. These lights have a strong edge over the slow, single-ended bulbs that made use of high pressure sodium lights.
LONGER LIFE SPAN
DE (double-ended) bulbs degrade a lot slower than single-ended bulbs. On average, after 10,000 hours of use, DE bulbs will still release about 90% of their light intensity.
BETTER SPECTRUM
Micromoles is a commonly used unit to count the number of photons in a plant grow light system.
DE HPS bulbs produce on average around 2,000 micromoles compared to single ended HPS bulbs that produce around 1,000 micromoles. This means that if you are growing with a single ended HPS bulb, you are using the same amount of power to create 50% less of usable light.
Technically the DE HPS can be used for the vegging stage but it is really geared for the flowering stage. As you can see from the graph, its wavelengths are concentrated at 600nm-680nm spectrum. This range of nanometers is also known as "red light".
DE HPS lights also emit more UV and IR then single ended bulbs. This is known to directly translate to increased potency and essential oil production.
Initially DE systems were designed to be only used with HPS bulbs but growers didn't like the idea of either having to veg with the HPS bulb and miss out on some of the blue light and green light spectrum or have an entire different light system for vegging. This is why manufacturers have altered the fixtures and ballasts to be able to fire up a DE MH bulb. As you can see from the graph, there is a significant increase in nanometers between 400nm-550nm, which is essential for the vegging stage.
BETTER LIGHT COVERAGE
Since DE bulbs have about 10-30% increase in light intensity and PAR output compared to SE bulbs, they will naturally have a better light spread.
Because DE lights are more intense then SE lights you can hang them higher and cover a larger area without sacrificing your light spectrum. With one 1000W DE lamp you can cover a space of roughly 5'x5' - 6'x6'.
Please note:
DE bulbs need to operate at a high temperature, which is why manufacturers advise against using any DE air-cooled reflectors. Flowing air over the bulb and causing it to cool can cause the bulb to be unstable and not release its lighting spectrum potential. That being said, you can still use an air cooled hood with a DE bulb, but you risk the potential of not providing your plants with the spectrum it needs.