I am currently in the process of getting my medical card and have been prepping my grow environment for what will hopefully be my first cycle next month.
I have spent around $700 getting my initial setup in place had been planning to use an older Sun System 2 all-in-one 400W HPS I bought in the late 2000’s and never put to use.
Yesterday I got the tent stood up, light hung about 19" above a thermometer probe, and a 4" 189 CFM inline fan with carbon filter strapped to the bars at the top of the tent. Of course, my next step was to swap out the HPS lamp for the slim MH and test what the ambient temps were with everything sealed up to get an idea of my veg environment. Unfortunately, with temps outside the tent at 70-72F, inside the tent it was around 86-87F where the canopy would be.
Currently intake is passive and I have yet to pick up the two small clip-on fans I plan to have circulating air within the tent. That said, I’m not sure how much I can expect things to cool down by changing those variables alone. At this point, I’m thinking I’m going to have to alter my lighting solution…
Cost is definitely a major consideration at this point so I’m not sure if I should cut my losses and just try to find a cheap-ish $90-150 LED setup or buy a remote ballast and lamp extension cord to the tune of about $85 and convert what I have to a remote ballast configuration. I’d prefer to stick with HID but I’m wondering how much I can reasonably expect temps to drop by removing the ballast from the tent. I thought some of you might be able to provide some insight.
Sorry for the long post. Thanks for any advice you can offer.
87F is cutting it close for heat but is do-able, although temps will get higher as volume decreases with plant growth and transpiration.
72F outside would mean your light and ballast are generating ~15F of heat. That seems about right for your tent size and lighting. Your bulbs are generating a majority of the infrared heat so you should be thinking of it in the simplest terms possible “Hot air rises, needs somewhere to go” So you’re not getting the heat out fast enough. Your fan seems sufficient are you running straight duct or with bends (reduces airflow) and where are you venting the exhaust?
Also what kind of RH are you seeing in your tent compared to ambient (this gives us a better glimpse at how efficiently our ventilation is working) ?
Before investing alot more money you’ll want to get those clip on fans you mentioned and angle them in such a way that they push the air around and up off your canopy. Again the idea here is to keep air moving continuously from intake to exhaust and exchanging the hot air from your canopy with cool air from your intake, if I read correctly, you just have an exhaust alllllll the way up top of that 6 foot tent with 6 feet of hot air below it, and nothing giving it a boost to the top. I think doing so will give you a good drop in temps.
Indoor summer growing has it’s challenges. and there’s lots of us here that grow and have grown in temps as high as yours, myself included.
My current setup is a good example, I have a 2x2x4 with ambient of around 78C but even with adequate ventilation and LED it’s still ~84C inside.
I also have a 7x7 room with 1000w HPS and temps get 90C+ in the summer. By the way this is with a remote ballast outside the room.
It will get better as summer turns to fall and the days get cooler too, which will line up with your delicate flowering phase.
Happy growing, be sure to share your adventures with us as you get your grow underway!
Another thing that may help you out is setting your lights so that they are running in the cool hours of the night and off during the hottest part of the day. Hope this helps. Blessings and happy growing!
You say you have passive intake and a 4" exhaust. How many cents are open? A general rule of thumb is intake should be 2x the exhaust. So you should have 2x 4" vents open for passive.
@Lucy247420
I’m going to grab some fans today and try another test run tonight. I’m hoping I’ll see at least 2-3 degree drop once air starts moving around within the enclosure. I did try to route the ducting with the fewest amount of bends possible but I will go back and see if there’s anywhere else I can make things more efficient. RH at the time of my last test was below 50% Somewhere in the upper 30’s IIRC. Of course, this will undoubtedly be higher once there are three 7-gal smartpots full of hydrated coco calling the space home! I will keep a closer eye on that metric during this next test.
Thanks again for your input. I’ll be getting my grow diary going ASAP. Genetics for my first run will FastBuds Gorilla Glue and Blackberry autofems. Stay tuned!
@DanzaKuduro
Going to try that very thing today and see what kind of changes I come up with in the ambient temps. Fingers crossed I can get it down 2-3 degrees F. If so, I’ll be a happy grower!
@ReikoX
In the Gorilla tent I had all three bottom ports fully opened. That is, the vent on the back with the mesh filter intended as a passive intake and the two on the sides intended for active intake ducting. I think a cheap intake fan pulling in one of those two side intakes with the others closed might be a better configuration and help get things to a more reasonable temp.
Based on the responses I’m seeing I think it’s worth tinkering around with cheaper components before converting my light or buying a new one. I still have yet to install the HPS lamp in the fixture and see what temps would be in flowering environment. I’ll loop back on that once I get the veg setup dialed in a little better.
forgive me