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The ThinkGrow Model H was released in 2019 (and updated since then). This light was included in our Top 13 BEST LED Grow Lights of 2021 review. Read on for the full review and my thoughts on this fixture.
The ThinkGrow lineup includes five LED grow lights:
The Model I and Model I Plus are top lights that can be used in grow rooms, greenhouses, anf also in grow tents. The main difference between the two is that the Model I Plus puts out a little more light and has a fully controllable spectrum with separate control over the UV white, deep red, and far red. The Model I only allows control over the full spectrum and far red channel.
The Model H and Model W are intended for flowering, while the Model V is meant strictly for veg, given its lower light output. The Model H, has an adjustable spectrum via a separate deep red boost channel. The Model W and V have a fixed full spectrum and an additional far red channel.
ThinkGrow designed this light to be modular which allows for compact shipping and removable and replaceable bars should one bar ever fail. The bars are fairly lightweight, feel pretty sturdy, and simply snap into the center driver assembly.
Once put together, the fixture is 45"L x 44.6"W x 4.44"H and weighs 38.8 lbs. The eight bars stretch nearly to the edge of a 4x4 tent. On one side of the driver assembly, you will find the power cord and controller receptacles. The other side houses the interface with the onboard dimmer and grouping control. A cord and NEMA 6-15P plug is included in the box. You can choose to add a NEMA 5-15P 120v adapter plug at the time of order.
This fixture can be used straight out of the box, or you can hook it up to the Trolmaster Hydro-X HCS-1 or HCS-2 controller. Trolmaster makes the Thinkgrow fixtures so the units integrate nicely. The Trolmaster HCS-1 controller is a more affordable, popular option.
To use this with the ThinkGrow light, you need a Trolmaster LMA-T adapter which interfaces between the light and controller. With the controller, you have control of up to 256 total lights, and are able to group them. In addition to the lights, the Hydro-X controls HVAC systems, mini-splits, dehumidifiers and humidifiers, and CO2 generators or regulators. With the free Trolmaster App, you can access all of the settings and alerts on the system from anywhere.
Ratchet hangers are not included with each light.
This fixture comes with a 5-year manufacturer’s warranty, is DLC-listed and ETL-certified for commercial grow applications, and is IP56 wet rated.
ThinkGrow does not disclose the brand or model of diodes that they use. Given the high efficacy and light output, I can conclude that they are good diodes. The Model H uses full spectrum white diodes and 660nm deep red diodes. These are on separate channels and can be adjusted independently. There is no UV in this fixture.
For veg, you will want to turn the deep red channel all of the way down. After doing this, you will notice that there is still some deep red lights on (turning the red channel down to zero doesn't completely turn all of the deep red off). We recommend turning the red channel to 100% for flower. The PAR efficacy of the fixture will go up when using a higher red to white ratio in the spectrum.
The Model H comes in at 2.7 umol/j with a light output of 1700 umol/s.
At full power, the unit draws 630 watts and 5.24A on 120 volts, according to ThinkGrow. With my own Kill-O-Watt meter, at 112 volts, I measured the fixture to be 675 watts at 6.06 amps.
On 240 watt power the Model H will draw slightly fewer watts and half the amperage.
The heat output is 2150 BTU/hour.
Like grow lights similar to the Model H, the light is designed to cover a 4x4 to 5x 5 area, depending on how much light you want to deliver to your plants. 5x5 areas are 36% larger than 4x4 areas so the light hitting the plants at this coverage area will be significantly less, assuming you are filling the entire 5x5 area with plants.
ThinkGrow recommends using this light as close as six inches from the plants in a 4x4 area. Based on my PAR measurements, 12-18” seemed to be a good distance in a 4x4 grow tent. Due to less reflectivity outside of a tent, 12” or closer would be a good hanging height for one or a few lights. If you have a lot of these grow lights in a room, you can hang them farther away from the plants due to the higher availability of overlapping light.
For veg, you can dim the fixture down to 50% and use them in the same 4x4 to 5x5 footprint without adjusting the height.
Here is the PAR chart that ThinkGrow provided for the Model H in a 4x4 area. I do not think these were taken in a tent. The average PPFD is over 1000 umol/s when hung at 6”.
Overall, I really liked this fixture. It was the first bar fixture that I have reviewed that I had to assemble myself. There are a few other lights on the market that require assembly, like the PhotonTek X 600W Pro LED, but self-assembly is not extremely common. Everything snaps together so it is really easy to assemble - no wiring required.
The light output, efficacy, and build-quality are excellent. I like that these lights are made to integrate easily with the Trolmaster Hydro-X controller which makes sense since Trolmaster is the parent company of Thinkgrow. Growers looking for some deep red spectrum manipulation will like this light too.
While an excellent light, there were a few things that stood as negatives:
1) The connection between the bars and the driver box is a little loose so the bars can rock up and down when bumped. I used a straight edge to get all of the bars inline and the same distance from the bottom of the tent before taking the PAR measurements. You also want to make sure the bars are snapped in all of the way otherwise they might fall out when moved. While the bar issue was noticeable, I don't feel as though it would in any way affect your grow.
2) I’m not sure if this was just the light we received, but the dimming percentage on the fixture did not match the wattage draw. For example, the 10% intensity did not match a 10% power draw on the Kill-O-Watt meter. Nor did 50% intensity match a 50% power draw from the meter. Therefore, I would not use the percentage as an absolute number, but more of a relative number when adjusting between intensities.
3) This is only an issue in a 4x4 tent: the power cable was hitting the rear of the tent and the front of the light was pushed a little forward. When the light is used in a larger tent, like a 5x5, or in a grow room, this would not be an issue. Be aware that the light will fit in a 4x4, but if you have any negative pressure in the tent, the tent will start to squeeze around the light.
Those are my only gripes about this fixture and the positives certainly outweigh the negatives.
The Model H is currently listed at $1,350. It’s more pricey than many other grow lights with a similar build and light output. You can also check out the Model W if you want a light that is very similar to this one, but is $250 less expensive. It puts out just a little less light and you don't have the deep red spectrum control. The price tag of the Model H is, in my honest opinion, justified, due to the quality build, spectrum control, and smart integration into the Trolmaster controller system.
There is a link below for the ThinkGrow Model H product page if you want to learn more or purchase this fixture. These lights ship for free in the lower 48 states with no tax in the USA.