The Best Small Grow Light 2018We have tested a range of small grow light systems to determine what is the most efficient, what has the best spectrum and how much they cost to buy and run. The models selected are:
- MARS 300
- Optic 1
- Viparspectra V300
- Lumii Envirogro T5 Fluorescent
- HGL Quantum Board 120 4K
- MIGRO 100
- 150W HPS with digital ballast
The tests were carried out in a 60cm x 60cm (2ft x 2ft) grow space with highly reflective walls. We hung each grow light at the recommended hanging height (details at the bottom of the article) and recorded 16 PAR measurements (light intensity in units for plants, units are umols/m2/sec PPFD). The 16 measurements can be averaged and the total PAR output onto the grow area (PPFD) from each light can be calculated.
Grow light PAR output (PPFD, umols/m2/sec)All seven grow lights selected were tested in the same environment and here are the results:
Grow light efficiency (PPFD/Watt)
The grow lights are different sizes. To compare them directly we divide the PPFD output by the power consumed in Watts to measure the efficiency of each light. This is a measure we can use to compare each grow light fairly.
Grow light spectrumWe used a spectroradiometer to analyse the light spectrum from each light and show you the comparison:
The Infra red (IR is the heat output) and the Ultra Violet (UV) ouput from each light and are not considered to contribute to plant growth. The balance of blue, green and red determines the type of growth you will get from the grow light spectrum. The % of blue light is most critical to optimum plant growth. Between 15% and 20% blue light is considered optimum for yield. Any less blue light and the plants are likely to stretch and any more than 20% is wasteful as it will not generate as much growth. Grow light spectrum are most efficient when the blue is mixed with green and red. The % mix of green and red is not critical as both spectrum are very close in photosynthetic efficiency. Please see our article on the best grow light spectrum here
Grow Light Cost Comparison
Each grow light is different in size and outputs a different amount of PAR light. To compare these lights we have calculated the fixture and running cost based on delivering a target PPFD level across the 60cm x 60cm (2ft x 2ft) grow area of 600umols/m2/sec. The target PPFD output for the light is therefore 600umols/m2.sec x 0.36m2 = 216 PPFD
For example the Lumii T5 fluorescent fixture outputs 75 PPFD. We need 216/75 = 2.9 Lumii T5 fixtures to deliver the target 600 PPFD average to our grow.
The fixture cost in this comparison is therefore 2.9 times the purchase cost of a single fixture. The running cost is for 2.9 times a single unit to achieve the target PPFD level.
- Lumii Envirogro T5 fluorescent 4 x 3ft tubes 100W (hanging height 10cm)
- 150W HPS with Lumatek digital ballast and hammered aluminium wing reflector 165W (Hanging height 25cm)
- Viparspectra V300 132W(hanging height 35cm)
- Mars 300 121W (hanging height 30cm)
- HLG QB 120 4K 61W (hanging height 30cm)
- Optic 1 54W (hanging height 27cm)
- MIGRO 100 107W (hanging height 30cm)
- Grow area: 60cm x 60cm (2ft x 2ft)
- Grow area walls: Silver mylar, diamond pattern 16 PPFD measurements taken for each test.
- Spectrometer: Assensetek Passport
- Quantum Sensor: Apogee SQ500
Fixture cost is a quantity of light fixtures needed to generate 210umols PPFD. This equates to about 600umols PPFD average across the 60cm x 60cm grow area. Fixture cost based on todays prices Power consumption based on generating 210umols PPFD over three years. Lights are on for 16 hour per day and energy costs of 17c/KW hour. Lights with dimmer adjusted for 50% normal level for half the grow time.