Have you measured the temperature at the leaves with an infrared thermometer? If the room temperature is 89 F with HPS in reflectors, guaranteed you have over 93-94F at the surface of the leaves. A temp range like that is a no go. Remember that what matters the most is the temperature at the surface of the plants, not the room temp. The room temp is just an indicator which can be way off what you imagine if you are growing with HPS in reflectors.
Also, you got to check out the VPD chart. If you have higher temps you can compensate by raising humidity. Definitely have reliable instruments for these 2 factors, temperature and humidity.
I dont have an IR thermometer (and I'm way too poor to afford one, that's why I growing my own medicine, can't afford to buy it). Anyways, I have placed the temperature sensor at several places in the grow tent and yeah it sure does fluctuate even within a small closed space, but 90F is at the canopy.
90 is hot but it's not crazy hot. Is it a consistent 90 or does it fluctuate, like with your house's AC or something?
200W is a lot of light to give up just to save a few degrees of heat.
Yeah it's a conundrum for sure, I don't want to give up 200W of light, and also this may just be an old wives tale, but I have read and been told that dimming a bulb lower then what it's rated for shortens it's lifespan. I don't know how true this is but if at all I would like to extend the life of this bulb as much as I can. I splurged on a $120 eye hortilux HPS bulb over the $20 vivosun one I was using, it was like my entire months savings, but I want this crop to be good. This like my 5th grow and they have all pretty much sucked so far, got weed but meh not great quality.
It doesn't fluctuate much, when the lights are on my room (which the grow tent is in) is about 75-77F and tent is 90F, when lights are off my room can go down to 72F and the tent is about the same temp -1 maybe to my room (so lowest 70F). That's a whole other issue I've been grappling with, it possibly getting too cold in there when the lights are off but that's another financial investment of a heater that's currently not in the cards for me. I'm sure it's fine.. lol.
Did I mention that it should have been well below 0 outside now in Ontario Canada, but we have had almost summer like weather all autumn and even now into november? Don't know how the extreme temps outside are going to affect things but uh cross that bridge when I get to it.
I did a summer run in a 4x2 with a 600. Had to run the intake fans pretty hard but, I got the job done while running the temps in the 91-93 range. Never showed any signs of heat stress. Doing a new run now and its still warm and humid here. Temps been right at 90-91 in tent past week and still looking good with no stress with a different strain.
I actually have passive intake. When I had a 4" fan drawing air in the temps actually went up considerably. I also have these DIY filters I put on the intakes so the tent is always getting clean air and has signifigant negative pressure, so only clean air getting in there. Attached are 2 pics, I have 2 of these filters and 2 holes open for intake.
Where are you exhausting to and getting your intake air from?
The air is coming from inside my bedroom and it is exhausting outside of the house. Attached is a pic, just a wooden board with 2 6" holes cut into it and literally taped into my window lol. I need to get some insulation very soon but fortunately the temperature outside has been warm (too warm for my region
).
To measure temps @paperov I have an arduino microcontroller with a DHT22 sensor from which I can collect and plot the temp and rh (rh on the sensor is broken though) in excel, and it is just above the canopy on the side. I also have a remote sensor from a cheap temperature sensor that is sitting within the canopy. Both temps read close to the same, but I try and keep sensor away from direct light, which is hard when you're trying to take the canopy temp. I am working on getting a working hygrometer right now, it's a matter of when it's delivered to me when it gets installed.
Last picture is of my plants yesterday, day 12 of flower (before the daily tuck, and yes I will be defoliating HEAVILY when they finish stretching). They all look healthy, I am just not sure if the temps have been stiffling their speed of growth or not, I have never grown these strains before (blueberry and peyote critical).
