The Future is Bright! (as long as you choose the right grow lamp)
There is a bewildering number of different brands and models of 600 watt grow lamp on the market. If you are putting together the equipment for your first grow, or just looking to replace your ageing grow lamp, how can you know you are making the best choice?
Prices for 600 watt grow lamps vary a great deal. At the lower end, one can be had for as little as £12.95, while higher-end lamps can cost more than twice as much at around £29.95. But do the more expensive lamps justify their premium price?
We rounded up a sample of all the single-ended 600 watt lamps that we stock (and some we have previously stocked alongside samples we’ve been sent), and then performed a comparative test on them to find out which are the good ones and hopefully find which are the winners in the 600 watt HPS category. We tested the following 600 watt HPS grow lamps:
- Gavita Enhanced
- Sylvania Grolux
- Sunmaster Deluxe
- Sol Digital
- Lumii Black
- Ultra Vivid
- Lumii Sunblaster
Most (if not all) 600 watt grow lamps look very similar. Usually, the main visual difference in the lamps is the writing on them which identifies the manufacturer and sometimes the part number. The glass jackets all look very similar, as do the elements and their internal wire support frames.
The human eye is not a good enough tool for assessing grow lamps. HPS lamps produce an intense orange-red light. All of the different models are so bright that it is virtually impossible for the human eye to discern which ones are the brightest. The differences in the colour spectrum that they produce, again are too slight to be judged by human sight alone.
In order to make fair comparisons, we chose a digital ballast (an Adjusta-Watt), and a fairly commonly used Euro (or barn-type) reflector; which was suspended at a fixed height from a rigid frame. The setup needed to be consistent – in other words, it needed to be an identical testing environment for all the lamps. All unnecessary movement of the equipment was pretty much eradicated and a single point was chosen beneath the reflector to measure the PPFD.
In an ideal world, we would measure the total PPF output of each lamp. Unfortunately, to do this we would need something called an integrating sphere which is an incredibly expensive piece of equipment and is rarely found outside of a laboratory. However, in a fixed system, the PPFD at a fixed point is relative and proportional to the total PPF output of the lamp.
Each lamp was given 3 hours to warm up, settle down, stabilise, and burn in a little. Ideally, we would have allowed a longer burn-in time. The PPFD was then measured at a fixed spot with our Li-Cor PAR meter, and a snapshot of the spectrum was taken with our Sekonic C-7000 spectrometer. Lamp swap-outs were performed almost surgically with the utmost care being taken to not allow any equipment to move. PPFD was measured in µmols/m2/sec.
We also used a plug-in power meter to measure the amount of power being drawn from the mains outlet. We thought that different lamps might draw different amounts of power, however we found that in this setup (which includes a digital ballast), all the lamps drew exactly the same amount of power (609W). This might be due to the Adjusta-watt digital ballast control circuitry accurately delivering the right number of watts into each of the lamps. It may be the case that if we had used a standard magnetic core & coil type of ballast, the electricity draw would have been different for the different lamps. We realised that actually, having the same power draw across all of the lamps from the wall was not a bad thing. It meant that any rogue lamp which drew more power and thus achieved high PAR reading was not a possibility using this ballast. It provided a much more level playing field for all the lamps.
So, the expectation was that the better (more expensive) lamps would output more PAR light and possibly a better spectrum. For the test, we’ve included the spectrum graphs for each of the lamps in this report. At a glance, the spectrum graphs look pretty much the same, but there are small and important differences.
It’s also worthwhile remembering that HPS lamps concentrate their output in the orange-red part of the light spectrum; light in this region is the most efficient for promoting flower and fruit production from a plant.
Many growers will know that there are 2 types of chlorophyll in a plant – chlorophyll a and chlorophyll b. Each has a peak in the blue part of the spectrum and a peak in the orange-red part of the spectrum. Although chlorophyll is not the only compound in plants that collects and converts light to energy, it is the one that is most commonly known and understood. The actual wavelengths that trigger peak photosynthesis in chlorophyll are:
Chlorophyll a – 400-450nm (blue) and 660nm (orange-red)
Chlorophyll b – 425-475nm (blue) and 640nm (orange-red)
I will repeat that chlorophyll does not tell us the whole story. There are several compounds within plant tissue that can collect light. The energy collected by these other compounds from light is then passed on to the chlorophyll which then performs the energy-to-sugar conversion process. The relative amount of photosynthesis produced at all the PAR wavelengths is depicted by the McCree curve (which we have overlaid onto our spectrum graphs). However, it would stand to reason that as well as stimulating the other light collecting compounds within the plant, it would still be quite important to drive the chlorophyll directly with light at 660nm and 640nm.
The McCree curve gives an idea of how photosynthesis is produced by different parts of the light spectrum. It is interesting to note that although a photon of blue light contains more energy than a photon of red light, the photon of red light will actually drive a similar amount of photosynthesis as one of blue light. However, because it takes more energy to produce the blue photon, you will get more photosynthesis by using your electricity to produce red photons. The McCree curve illustrates this by showing (in relative terms) how much photosynthesis is driven across the PAR spectrum (400nm-700nm). For this reason, we have overlaid the McCree curve onto our spectrum graphs. For plant health and efficiency, we were looking at the width of the main part of the orange-red spectrum (mostly around 600nm) and how much was relatively produced slightly higher up at those key wavelengths of 640nm and 660nm.
9) The FireFly HPS Lamp
The FireFly is a budget-end HPS lamp. It can be found around the internet for the remarkably low price of about £12.95. As such, it is one of the cheapest of the bunch. In this test the FireFly was putting down 667 µmols/m2/sec. The spectrum:
Although the FireFly produces a similar orange-red light as all HPS lamps, the spectrum shows us that its main output band in that region is actually a little bit narrow and it produces comparatively less light from 630nm upwards. Overall, this lamp does not offer the same performance as the more expensive lamps in this test.
8) The LUMii Sunblaster HPS Lamp
One Stop Grow Shop don’t stock the LUMii Sunblaster, but it is available on the internet for about £15.00. We clocked the Sunblaster’s output at 724 µmols/m2/sec which, while better than the FireFly, it still does not approach the light output of the better grow lamps in this test. The spectrum:
The main orange-red band is slightly broader than the FireFly and has more output from 640nm upwards.
7) The LUMii Black HPS Lamp
This would seem to be the replacement lamp for the LUMii Sunblaster lamp above. It can be found for about £14.95 at certain outlets. The LUMii Black kicks out 745 µmols/m2/sec which is definitely a worthwhile improvement over the LUMii Sunblaster. The spectrum:
The spectrum looks like it has been very slightly improved too. The main band is very slightly wider and the light output above 640nm is very slightly higher too.
6) The Ultra Vivid HPS Lamp
The Ultra Vivid HPS lamp is available from One Stop Grow Shop for £14.95. This little fella kicks out 747 µmols/m2/sec which is in the same ballpark as the LUMii Black. The spectrum:
The spectrum coming out of the Ultra Vivid is the best so far with the orange-red band being the widest. The output above 640nm is slightly higher than the FireFly or the LUMii lamps. This will please your plants and will likely lead to better plant health and yields too.
5) The Omega HPS Lamp
The Omega HPS lamp at £19.95 is generally thought of as being a good budget lamp. It is frequently purchased as part of a budget grow light kit. However, One Stop Grow Shop stocks this lamp for purchase separately. In this test the Omega was putting down 770 µmols/m2/sec which is the highest so far. The spectrum:
The spectrum shows that the approximate intensity (relative to the peak intensity) above 640nm is approaching that achieved by the Ultra Vivid. However, the increase in PAR light output that you get with the Omega means higher yields could be possible.
4) The Sol Digital Lamp
The Sol Digital lamp retails for £19.95 at One Stop Grow Shop. It provides a slightly greater output than the Street Lamp giving out 780 µmols/m2/sec at our test point. The spectrum:
The width of the main orange-red band is good and there is a nice amount of output above the 640nm region. We know that our customers have great results with this lamp which would back up the findings from the testing. At 780 µmols/m2/sec PPFD at our test point, it can drive the most photosynthesis of all the lamps so far.
3) The Sunmaster HPS Deluxe Lamp
The Sunmaster Deluxe has been around for many years and it has built its reputation on the claim that it outputs 95,000 lumens (which is considered very high for a 600w HPS lamp). It retails for £24.95. Lumens does not directly translate into PAR. In other words, a very high lumen output does not necessarily mean that it will drive the highest levels of photosynthesis. It simply means that it appears particularly bright to our human eyes. Fortunately for Sunmaster, the PAR light output is very good too – it was measured to be 781 µmols/m2/sec which just barely beats the Sol Digital. The spectrum:
The spectrum would have been better if the orange-red spectrum was a touch wider and there was slightly more light output above the 640nm region. Still, the Sunmaster Deluxe is still a highly popular lamp and with its great PAR output has the potential to produce very pleasing sized crops.
2) The Sylvania Grolux Lamp
In number 2 position, the Sylvania Grolux HPS lamp is another lamp that has proved its popularity over time. It claims to produce 90,000 lumens (5000 less than the Sunmaster). It would make sense, given the lower lumen output, that it is slightly cheaper at £22.95. However, as we know, lumens do not necessarily correspond to PAR output and indeed this is the case here. The Sylvania Grolux produced 802 µmols/m2/sec – the best so far, and a bit higher than the Sunmaster. The spectrum:
Not only is the PAR reading very high but the width of the orange-red spectrum is the best so far, as is the amount of output in the region above 640nm. This lamp should really deliver the goods in terms of yields and plant health. At this price, how could you go wrong?? – Great value-for-money!
1) The Gavita Enhanced HPS Lamp
And so we finally come to our winner. The Gavita Enhanced HPS Lamp was introduced a few years back with a design meant to make the most of digital ballasts. At £29.95 it is the most expensive of the bunch, but the performance reflects this as it puts down 810 µmols/m2/sec. This puts it in first place. The spectrum is impressive too:
The spectrum is almost the same as the Grolux. It has a great width to its orange-red band and output above 640nm is excellent too. It also puts a little icing on the cake with a pretty high output in the far-red. During flowering far-red can improve the flowering response in many plants. Part of the design is that it has a much improved element support frame inside. This makes it less likely to distort due to the high frequencies produced by digital ballasts. Great PAR light output, great spectrum, and robust design go together to make this lamp the top dawg.
The scope of this test meant that only one sample of each lamp was tested. It is entirely possible that we had some particularly good examples of some lamps and some lower quality examples of others. It would have been better if several examples of each had been tested and an average taken. For this reason, the results should only be used as an indication rather than for anything absolutely definitive.
This roundup of HPS lamps shows that spending that little bit extra on your grow lamp really does make a difference to the quality. A small additional spend at the start of your grow can reap huge dividends in the size and quality of your crop.