In parts 1 & 2 of this series we introduced our new Li-Cor Quantum meter and we talked a little bit about why this expensive but precision piece of kit is the correct one to use for grow lamp testing and comparisons.
With all that out of the way, we will now move on to introducing our test set-up and our experimental procedure:
For this test, we need an environment that is as close to a real-life set-up as we can get. We therefore decided to use a quality 1 metre x 1 metre grow tent which is a one of the popular choices for a hobby grower using grow lamps in the 250 Watt to 600 Watt range. Our shop staff would generally recommend a 1 metre square tent for someone wishing to use a 400 Watt HPS grow lamp. This size of tent is clearly a good choice given the range of lights that we plan to test. Easy Rolls were installed to make an easy job of raising and lowering the lights.
We attached the Li-Cor Quantum Sensor to an available camera tripod. We decided on this arrangement because we need a firm and stable stand which can be raised and lowered without too much hassle. The camera tripod also offers a top surface with a gimble enabling us to angle the sensor towards the lamp to get the most accurate measurement of the amount of PPFD hitting that particular spot.
The camera tripod also makes it easy to move the sensor around in the tent to test PPFD at different points. We feel this is important because for the following reason: measuring the PPFD at different heights directly under the different grow lights is fairly quick and simple. However, the region directly below the lamp is only a small part of the total grow area. For a comprehensive test, we need to test PPFD at various different points at the sides and the front and rear of the tent as well as in the corners.
Apart from that, the main other piece of equipment is a tape measure for accurate measurement of the distance between the lamp and the sensor. Armed with that and lots of paper and a pencil, we are ready for the actual testing which will we will be starting in the next part. We will begin our testing with the Prakasa 300 Watt LED grow lamp:
The Prakasa 300 Watt LED grow lamp is not a cheap piece of equipment. However, it is representative of what a serious hobby grower might consider buying rather than a 250 Watt or 400 Watt HPS grow lamp. Prakasa have certainly made a nice job of making it. It contains the following LEDs:
- Deep Red 660nm: 8 x 3w LEDs + 19 x 5w LEDs
- Red 630nm: 13 x 3w LEDs + 33 x 5w LEDs
- Orange 610nm: 12 x 3w LEDs
- Blue 460nm: 8 x 5w LEDs
- White 15000-20000 Kelvin: 6 x 3w LEDs + 6 x 5w LEDs
- UV 410nm: 2 x 3w LEDs
- IR 740nm: 1 x 3w LEDs
The Prakasa emits a good range of different wavelengths and would seem to be well thought out. Cooling fans on the top of the unit ensure that the LEDs do not overheat which could affect their 50,000 hour lifespan. The manufacturer claims that this grow lamp can cover an area from 1 – 2.5 metres squared and gives out light equivalent to that from a 600 watt HPS. This is quite a claim and we shall enjoy finding out if they are right!
Before signing off this part, we switched the unit to show you the inside of the grow tent bathed in an eerie pinky-purple light!
In part 4 of this series we will be beginning the actual testing and bringing you some juicy data!