My auto Tent is having an issue with high heat and RH. During the day, it is reaching 80F and 73%RH. Under the canopy, it is a nice 74F and 54%RH. The leaf temps are around 74F during the day with the lights at 11 inches.
I have a 6" exhaust fan, a 9" osc fan and air intake from both bottom sides of the tent. The room temp is always 4-5 degrees cooler. The probe is set at canopy hight.
The tent is crowded! I have two Banana Kush Autos. One at 10 weeks that I have topped and done a lot of LST with,
and the other at about 8 weeks, that I only topped. The tent is a 2*4 and the sides are pulled in due to negative pressure from the exhaust fan.
I have ordered the extender bars for the tent to help with the NP. I am hopeful this will also help with the heat and RH by increasing circulation throughout the plants.
Yes it sounds like air flow issues, or the the way you are talking reading. In my 2x3 there is both a 4 inch exhaust and intake fan, and two small clip on fan inside. Typically there is a slightly higher temperature in the top, and slightly higher humidity in the bottom of the tent. But the difference is never more than 5 point on either, and it is typically 3 points difference.
I usually don’t take reading between the light and the top of the canopy. Some temperature sensors will need to be shaded from direct light. Especially larger sensors or ones that are encased with a cover.
Are you saying 11 inches from light to canopy? That is really close.
Thanks for some confirmation. The light that is that close is only a 100w LED and the next one over is a 200w LED. I have the height at 11" as that seems to be good for the plant as it is growing very quickly now. I adjust the lights up an inch or so daily. I’ve only got maybe another 7-8" to go up.
Sounds like maybe you could strip some fan leaves to open up the canopy and allow more air flow from bottom to top of tent. I would also look at what you have open for passive intakes and look at potentially opening more if you have them. Judt make sure it’s protected from light leaks for flowering.
I dont have totally enclosed space, i bought one of those artic airs for 40.00 bucks. Dont think it cools a room as fast as it advertises.
Aimed where you need it, it will cool it alot specially aimed at the canopy.
Also, its a great source for addind Rh.
We are home most of the time. The reservoir dont last all day, but, if your canopy peaks hi temp at 2pm, a timer set to come on will get you through the rough period.
That is the bottom line to the effort “What does the plants look like”?
I have conducted some tests with temperature sensors. Here is a little more on this. Using the pictured Fluke with its tiny beaded sensor located on the end of the wire, and the temp/humidity sensor. First insured that both were reading the same by setting them together out of any direct light.
Next put both directly under the the light at about 18 inches. The large enclosed temp/humidity sensor had an oven effect on its sensor and reads higher than it really is. The tiny sensor on the Fluke was not effected by the direct light. So one needs the be careful when taking temperatures under the direct light.
I mainly use the temp/humidity sensors that are in the picture. I like to hang them by a small chain in the canopy at about 2/3 of the height of it. This shades the sensor, and gives the humidity of the air at the plant.
@JimWantsToGrow May not help now… But what light are you using… brand? Some give off way more heat than others.
Depending on the light… In the future you may be able to upgrade to a better more efficient cooler light.
When I switched to leds… I went burple Amazon lights… The heat was terrible… Couldn’t keep up… With new hlg lights… It solved my heat issues.
Thanks, but I have a total of 300w in the tent. I do think I can upgrade, but looking at the SF SE4500 for my next grow., Vs. the two ACI lights in there now.
I’m running a 22 and a 24 from AC Infinity in the tent. The heat from those is terrible, yes. Each puts off over 120 degrees. I have the exhaust vent sitting right over the lights to pull off their heat, but I will be upgrading to the Spider Farmer SE4500 for my next grow. I have an SoG of Wedding Cake Auto built and ready to go when these two plants are done. I need to have all this understood and controllable by then.
These are the two plants in the tent right now. I don’t have a better picture of the overall, sorry. The room is a 3*5 with an AC inlet vent that is open all the way. AC set to 72. It is usually around 1 degree cooler in this room.
I had some personal issues that through off my timing this grow… I grow regular Photoperiod… Vegged for too long…in flower a couple/few weeks… Has me sweating… The stretch is almost over… Hopefully, I can raise my light more.
Are you to SoG with autos or Photoperiod for the next grow? From seed or clone?
Just saying… Hlg has great lights. Will never gave you saying… Should I have gone with something else… Plus their customer support and service is top notch.
I took advice from all, and defoliated, and added an intake fan for more airflow as well as shielded the “metal-tipped” probe from the direct light. It dropped 5 degrees instantly.
I will be upgrading the lights for my next grow. I should be harvesting BKA1 around the first week of Aug and BKA7 around the end of Aug.
I have a couple of ILGM journals going now if anyone is interested. My Banana Kush Auto grow and I have Skywalker OG in another tent for my Fems.
@Growmoredank and @Ickey thanks for the info on HLG. @Ickey very useful info, thanks! @dbrn32 defoliation has provided more clearance for airflow., Thank you.
@ChittyChittyBangin , do you have your probe tips covers from direct light? I didn’t and it makes a huge difference
I couldn’t understand why ACI was reporting higher than everything else in the tent.
She should be a out 4 weeks in. I’m brand new at this, so I’m guessing, based on pics I see and timing for autos.
I’m growing autos in this tent. Banana Kush Auto to be exact.
My SoG setup is a tote RDWC setup. I have a batch (5) of Barny’s Farm Weeding Cake Autos I’m going to grow for the wife. Wedding Cake is her fav.
I have learned that LST will dramatically change the size of your plant. The two sitting side by side above are only about 2 weeks apart. The big one I manipulate probably more frequently than I should. I topped it, broke off a couple of branches early on, snap a small root or two. She’s been through hell, but keeps growing right back. Lol
I don’t expect a huge yield from this one just based on what I’ve read. I hope I’m wrong. Time will show
Glad to help! This is my problem with the average grower trying to maintain VPD. A few degrees off on a couple readings will get you into trouble quickly.
Your plants look very good, by the way. Looks like a tiny bit of canoeing on the top leaves, but no major signs of heat stress.
Also when are ready to upgrade your light. I would suggest that you give serious consideration to a HLG 350 Diablo. The rectangular shape and output would be great for that 3x5. It may be available as a refurbished unit when you are ready.
Putting the bars in should help the walls from physically getting sucked in, but the negative pressure will still be there. The negative pressure is basically your exhaust fan telling you that it can pull some more CFM, but you’ll have to increase your intake area to free it up. If you have a lot of negative pressure, you want to bring it down to where you have just a little bit. Turn the exhaust fan to max power & add enough intake area until you lose suction, then take away a little intake area to put a little negative pressure on the tent, & you’ll be right around max CFM of your exhaust fan, but still putting a little velocity on the intake air due to having the little bit of negative pressure.
That would dial in the flow in front of the intake side of the current exhaust fan. Any carbon filters or excess tubing or bends anywhere? If you dial in your intake side now, & then find other restrictions that you free up later like for example getting rid of excess tubing/ bends or installing a carbon filter with higher flow, then go back & turn the fan up to 100% again & re-dial in the intake area to provide for the potential flow increase.
Thank you @PhotoFinisH . I did open an additional inlet port on the tent. The extension bars just arrived, so I’m going to go put those in and see about adjusting my input flow a bit better.
