850W LED Grow Light — HPS Replacement
121
Small in Size. Immense in Power.
The direct HPS replacement that outperforms what it replaces.
The Fohse 121 was engineered with one goal: replace HPS and surpass it. At 850W, it delivers 2185 μmol/s of photosynthetically active light through a high-performance lensing system that drives photons deeper into the canopy than HPS can reach. IP66 rated, dual-voltage compatible, and built to last — the 121 is the fixture for growers ready to leave HPS behind for good.
Frequently Asked
121 Questions,
Answered.
What does the Fohse 121 replace?
The Fohse 121 is a direct replacement for HPS (high-pressure sodium) grow lights. It was engineered not just to match HPS output, but to exceed it — delivering 2185 μmol/s PPF with a high-performance lensing system that provides deeper canopy penetration than a single-point HPS source can achieve.
What is the PPF and PPE of the Fohse 121?
The Fohse 121 produces 2185 μmol/s PPF — the total photosynthetically active photons emitted per second. Its PPE ranges from 2.50 to 2.65 μmol/J, meaning it converts each joule of electrical energy into PAR light efficiently. Tolerance is ±10%.
What voltage does the Fohse 121 require?
The 121 supports both low voltage (120–277Vac) and high voltage (277–480Vac) inputs. This dual-voltage compatibility makes it one of the most electrically flexible commercial grow lights available, allowing growers to install it into existing HPS wiring infrastructure without a full electrical overhaul in most cases.
Is the Fohse 121 waterproof?
The 121 carries an IP66 ingress protection rating — fully dust-tight and capable of withstanding powerful water jets from any direction. IP66 is a higher protection level than IP65, making it suitable for facilities that perform regular washdowns or operate in high-moisture commercial environments.
How does the lensing system in the 121 improve canopy penetration?
Traditional HPS fixtures emit light from a single point source, causing PPFD to drop sharply with distance and limiting how deep usable light reaches within a dense canopy. The 121’s high-performance lensing system focuses and directs photons in a controlled pattern, maintaining higher PPFD at greater depths — increasing the proportion of the plant that receives effective light intensity.
What LED chips are used in the Fohse 121?
The 121 is built with LEDstar 5050 diodes. These large-format diodes are selected for their output efficiency and long operational lifespan — significantly outlasting HPS bulbs, which typically require replacement every one to two years due to lumen depreciation.
How large is the Fohse 121 and how much does it weigh?
The 121 measures 25″ × 16″ × 4.7″ and weighs 26.5 lbs. Its compact dimensions make it well-suited for lower-ceiling grow rooms and facilities where traditional HPS fixtures would be impractical due to height or space constraints.