Replacing your HPS lighting with LED

A greenhouse with lots of HPS lights

A greenhouse with lots of HPS lights


GrowFlux isn't the first LED manufacturer to tout LED technology to stalwart growers who have stuck with high pressure sodium (HPS) lights over the years. The most common reasons for not adopting LED we hear from growers are:

  • I'm waiting for the next generation of LED products to come out
  • There are too many outlandish claims made by LED manufacturers and not enough standardization
  • The spectrum isn't "right"
  • The efficiency claims aren't valid
  • I need the radiated heat for my crops in the shoulder seasons

We understand the concerns these growers have, and want to present an honest picture of our products so these customers can make the best decisions for their own situation. We hope to show that our FluxScale 600 top light is the industry's best HPS replacement fixture, but we want our customers to make this decision for themselves. Lets go into some detail:

Spectrum differences

Yes it is true, LED horticultural lights DO have a different spectrum compared to HPS lights, which are commonly used for flowering due to the high levels of red light. HPS lights also cover nearly the entire PAR spectrum, while many red/blue LED lights are missing PAR spectrum in the middle of the PAR range.

With GrowFlux tunable broad spectrum technology, growers can choose the spectrum that works for their unique situation while covering the entire PAR range from 400-700nm. In fact, we have developed light formulas which mimic the HPS spectrum nearly identically. While our spectrum is not an exact fit to the HPS spectral curve, the key aspect to our spectrum match is that the proportion of light in each spectrum band is very similar to HPS. This results in predictable flowering results for customers whom are accustomed to HPS fixtures. 


Having covered the spectral differences between HPS and GrowFlux LED products, there are a few other elements to touch on related to flowering. Since HPS lights are not tunable, precise manipulations to flowering spectrum are not possible. In addition, GrowFlux lighting products incorporate far red LEDs, allowing growers to further manipulate phytochrome response in short day flowering plants. 

Efficiency & maintenance

The most efficient HPS light on the market produces 2.2umol / watt with a brand new bulb. There, we said it - HPS lights are pretty efficient. Not all LED manufacturers want their prospective customers aware of this fact because many have trouble passing even 2.0 umol / watt efficiency. Keep in mind though that this efficiency figure is with a brand new bulb, and as that bulb progresses through its useful lifespan, the efficiency drops far below 2.0 umol / watt. With high efficiency bulb prices ranging from $70-90 each, and approximately annual bulb changes, the maintenance costs add up with HPS lights. 

Differences in light penetration

We have heard concerns over light penetration into the canopy with LED products from some growers. Since there is a lot of variation in LED fixture optics across manufacturers at the moment, this is not a surprise. We can speak to this specifically as it relates to GrowFlux products; our FluxScale 600AC version 2.0 fixture contains 318 LEDs with an approximate 130 degree beam pattern in a tight array (with outstanding thermal performance).

This LED array packs a serious penetrative punch directly below the fixture (the light from approximately 0-30 degrees from fixture center) . At high angles (between 60-90 degrees from the fixture center), we direct this light around this central hotspot on the canopy with our high efficiency FluxScale reflectors, resulting in highly uniform light. Our reflectors happen to be made of the same Alanod 9033AG material many HPS reflectors use. 

Heat & heat stress

Finally we have heard a lot about heating greenhouses with HPS lights - that the radiated heat from HPS lights is a side benefit to growers in cold regions such as Canada, the Northern US, Scandinavia, and the UK. While heating greenhouses with HPS lights might be a simple solution, we would like to point out that the efficiency is relatively poor from a lifecycle point of view, and this can cost growers a lot of money over time.