Too hot in your grow tent? You need to keep temperature well regulated for your plants, just a short amount of time at high temperatures can destroy the entire crop inside the tent. At our Kalamazoo location, summertime is upon us and it’s getting more difficult if not downright impossible to keep our grow tent temperatures in check without AC. It might be that the room temperature that your grow tent is located in has risen due to non-existent or inadequate air conditioning in your residence. This means the air you pull into your grow tent to cool it just isn’t cold enough to keep the temperature in the proper zone for healthy plant growth. Well, just so happens the sales staff at the HTGSUPPLY Kalamazoo store have a set-up that will show YOU how to properly use AC in your grow tent and keep temperature down!
We sat down with Zach, the HTGSUPPLY sales associate who is in charge of this system, for a brief Q&A regarding their set up:
What kind of equipment are you using in this set-up?
- AgroMax Large Sized Grow Tent
- Digital 600 watt Dual-Arc (MH/HPS) Grow Light with Open Air Adjustable Reflector
- Sherpa Brand Portable Air Conditioner by GoChill
- GrowBright CO2 Regulator and 20 lb CO2 Tank system
- Two BubbleBoy Deep Water Culture (DWC) Hydroponically grown plants
- One 16” Wall Mount Fan
- One 6” Clip On Fan
- Two AgroMax Equipment Boards (these boards are really cool, they mount inside the tent and you can hang your fans or controllers from them)
How often is the AC on?
Currently the Sherpa portable AC unit runs on high 24/7, this will keep the temperature inside the Grow Tent at 72 degrees during the light cycle and 62 degrees during the night cycle. A degree change of 10 degrees from day to night is expected by your plants. Variations of high/lows can cause stress and hermaphroditic features on some plants, especially if night time temperatures exceed day time temperatures.
How does the AC know when to come on?
The Sherpas have an always on feature that allows the air conditioner to be triggered by a remote thermostat set up inside the growing chamber. This can be a useful piece of information when purchasing an air conditioner that is going to be operated on an environmental controller or a digital cooling controller because some digital ac’s will not turn on and off through a trigger, this means that some AC units, once turned off by an outside trigger, will not reset to the “on” operation, but will reset to off.
Do you use an AgroMax Controller?
We do have one plugged in, however, because of higher temperatures outside the tent on our salesfloor/warehouse, the Sherpa runs constantly. However, if temperatures were lower in the surrounding room we could utilize the AgroMax Digital Cooling controller so that the AC would only run when needed.
What temperature do you keep it at?
Day 72 F 50% humidity
Night 62 F 50% humidity
Air must push out of the tent when it’s on so does that blow out all the injected CO2?
Air will always flow out of and into the tent simultaneously but at different rates. By keeping all the vent holes sealed and covered, you are drastically limiting the escape route of the CO2 gas.
Effusion/diffusion; gaseous molecules may flow very slowly through pores in the tent to reach equilibrium with outside concentrations. This will always happen but it is noteworthy to know that O2, N2, and Ar(g) all have lower molecular weights and will effuse at faster rates than CO2. [both O2 and CO2 will want to move out of the tent through this process]. Depending on the construction of the Grow Tent, this rate may be higher, as the AgroMax unit is constructed pretty well and the thickness of the wall material is at least twice what we have seen from some other manufacturers.
Pressure; gas will always flow from areas of high pressure to areas of low pressure i.e. from inside the tent to outside the tent. However, by sealing all major holes we can limit the movement of gas to small effusion-sized holes present in the fabric and the zippers.
What bulb/ballast/reflector are you using and why?
We are using an open-air adjustable grow light reflector for this setup. To get the absolute most lumens possible, you can use open-air reflector. Many customers use “Air Cooled Reflectors” in their grow tents which make it easier to direct the bulb heat out of the tent, but this will usually require some extra ventilation equipment. The nice thing about the AgroMax grow tents versus some other brands is that they have about twice the number of ventilation ports so you have many options for air-cooling. As for the bulb we are using the AgroMax Dual-Arc 600 watt HPS/MH Hybrid bulb with a Digital Greenhouse 600 watt digital ballast. We are using 600 watts because they are the most efficient lumen/watt ballast on the market. We choose the hybrid bulb to give our plants constant dual spectra (White/Blue from the MH tube and Red from the HPS tube)
Why don’t I want to just air cool an air coolable reflector? (Why open air?)
You may want to use an air coolable reflector, definitely may want to. But open air reflectors are how you get magazine-quality and commercial-sized flowers. If you have the ac for it NOTHING beats open air, nothing (no glass) in between the bulb and your plants is the brightest option.
What tent size is this and would it work for other sizes?
This is the large sized tent. Theoretically, as long as the BTU output of the AC unit is greater than the thermal output of the light and other equipment, then temperatures can be controlled. Although the smallest area I have ever worked in is the large sized tent in this store. All my consulting and growing experience comes from much larger growing areas.
Just an FYI, bulbs and other equipment have a heat output of about 3.4 BTU’s per watt. So a 600 watt bulb would produce approximately 2,040 BTU’s. So if you had a 2000 BTU AC unit, this would be just about enough to keep temperatures under control. Typically I would recommend that you “over-power” the AC by 30%, so if you wanted to remove 2000 BTU’s of heat, you would use and AC unit rated at least 2600 BTU’s.
How much electricity does the tent use (A/C, Light, Fans)?
Wattage drawn at 110v.
AC 1800 w
Digtal Greenhouse Ballast with lamp = 600 watts
16” Oscillating Fan = 60 watts
Pump = 3 watts
6” Clip-on fan = 25 watts
Total is 1888 watts
Total electric cost at 11 cents per Kwh=
a) AC unit and Fans
1.88 kW * 24 h/day * 30 days * 0.11 $/ kWh = $148
b) Grow Light:
600 w = 0.6 kW * 12 h/day * 30 days * 0.11 $/kWh = $24
TOTAL cost of operations (@ $0.11/ kWh) $172/month
Why are there both a 16″ wall mount and 6″ clip on fan?
We are using the 16” oscillating fan to distribute the heat pocket below the light. The small clip fan is being used push the hot air towards the cold air to prevent heat stratification.
Is there any other information or Tips you might give a grower looking to set up an Air Conditioned Grow Tent?
When using an air conditioner it is important to remember the cool air isn’t made by the air conditioner but rather the air is separated into hot and cold. You are going to have hot air created when you use any AC unit, and you need a way to transfer that hot air away from your grow tent. In the case of the Sherpa AC unit, it is located outside of the grow tent and the hot air radiates from back the AC unit itself but the cold air is directed through the tube directly into the tent.. Note: Larger portable AC units like the Yeti by GoChill offer a separate exhaust tube to more directly send this heat outside the grow area. There are several ways to deal with this heat build up on the outside of the tent if it becomes a problem.
- You can encase the unit (large box next to tent or adjacent room) and use a fan to either evacuate the heat from your residence or to push it through your existing house duct work to provide extra heat during the winter months. (best)
- Mount the ac unit on a shelf above the tent in a room that has tall ceilings and exhaust into the air space of the room surrounding the tent. (good)
- Have the tent in a large enough room so that the gas has enough room to expand and cool. (adequate, as pictured)
- Direct the heat from the AC unit outside of your house through the window or wall opening.
When choosing the proper sized ac unit for your needs you may also want to include the number and size of your plants into your calculations. Some plants produce some heat through rapid rates of photosynthesis and can produce somewhere in the neighborhood of 25-100 btu/plant/foot of growth. So if you intend on having 6 plants with 4 foot of growth per plant you may want to have an ac unit that is anywhere between 600-2400 btu greater than the thermal output of your light.
Looking for more information? Come on in and visit the best Grow Shop in Kalamazoo – HTG Supply. Looking for Grow Tents in Kalamazoo, we have a huge stock of Grow Tents and AC units to keep them cool. Of course we have the biggest stock and best prices on Grow Lights in Kalamazoo.
Looking for Hydroponic equipment in Kalamazoo – You’ve got to come to the store as we have over twice the stock of any store in the area. HTG Supply – Kalamazoo has it all, whether you are a beginner or seasoned veteran, we can help you be more successful in your garden. We have the equipment you need and the guaranteed lowest prices. Even better, we have in store professionals that can help solve any problem you may have and help you grow!
High Tech Garden Supply
1745 West Main Street
Kalamazoo, MI 49006