Switching from HPS to LED grow lights is worth it for most Australian indoor growers. Modern LEDs like the SANlight EVO deliver equal or better yields than 600W HPS at significantly lower electricity cost, with less heat to manage. The transition takes one cycle to adjust to, and most growers don't go back. This guide covers the real differences between the two technologies and how to optimise your setup after switching.
What HPS grow lights are and why they worked so well
HPS (High Pressure Sodium) lights are a type of high-intensity discharge lighting that produce strong output in the red and orange spectrum. They dominated indoor growing for decades and for good reason. In enclosed spaces like grow tents, the heat HPS lights produce naturally increased ambient temperature, boosted humidity when enough plant biomass was present, and helped maintain a favourable VPD. Many growers were hitting near-optimal conditions during vegetative growth without needing additional equipment. The light did the environmental work for them.
Where HPS falls short
HPS systems consume significantly more power than modern LEDs, making them expensive to run long term. During flowering, the heat they produce becomes a liability rather than an asset. High canopy temperatures reduce Brix levels and terpene production, directly affecting the aroma, flavour, and quality of the final product. HPS also lacks the spectral control that modern LEDs offer, and bulbs degrade over time and require regular replacement.
Why growers are switching to LED
Modern full spectrum LED grow lights deliver equal or greater usable light at a fraction of the power consumption. Lower electricity costs, less heat output, and a lifespan of 50,000 hours or more make them a better long-term investment. LEDs also give growers precise control over spectrum and intensity, which HPS cannot match. Where HPS created the environment for you, LEDs give you the tools to build a better one deliberately.
Where LEDs outperform HPS most clearly
LEDs excel in the late flowering stage. Because they produce less radiant heat, leaf surface temperatures stay lower, plants experience less stress, and terpene preservation improves. Brix levels can increase as a result. The final product from a well-dialled LED grow consistently shows better flavour, aroma, and overall plant expression compared to HPS at the same stage.
The magnesium demand increase under LED
A commonly overlooked factor when switching to LED is increased magnesium demand. Higher light intensity and increased photosynthetic activity under full spectrum LEDs means plants draw more magnesium than they would under HPS. Growers switching from HPS often need to adjust their feeding schedule and supplement with a Cal-Mag product, particularly in the vegetative stage.
Managing the environment after switching to LED
LEDs produce less heat, which can slow vegetative growth in cooler environments if not managed. Without the passive warmth of HPS, humidity often drops and VPD can shift out of range. To get the best results from LEDs in Australian conditions, most growers need a grow room heater for cooler months, a humidifier to maintain VPD during veg, a dehumidifier for flowering, inline exhaust fans with temperature and humidity controllers, and oscillating fans for airflow. Dialling in these factors is what unlocks the full performance advantage of LED over HPS.
Can you still optimise an HPS setup
Yes. Growers running HPS can still fine-tune their environment using dehumidifiers, humidifiers, temperature-controlled exhaust systems, and fan speed controllers. The fundamentals of environment management apply regardless of light type. HPS just requires more active cooling and humidity management during flowering than LED does.
Grow lights for Australian hydroponic setups
For a full range of LED and HPS grow lights suited to Australian conditions, including the SANlight EVO series and other high-performance options, browse the LED and HPS Grow Lights collection.