Environmental Question

I'm doing 55-65% RH and 78-81F during lights off.. are these numbers good enough to get me through my summer flowering? I'm not worried about during lights on, because my a/c unit will be running when the light is turned on.

Starting with my usual disclaimer of "I am no expert" I'd suggest that they will get through that, but I think that might be pushing it a little bit too much on dark temperatures and I think you may seriously run the risk of bud moulds or fungus growth at that humidity level.

If you cannot negotiate the dark temps, I'd advocate dropping your humidity down to as low as 30%. I always prefer to be slightly too dry on the flower just to be safe...

Humidity that high is asking for all kinds of issues from bud rot to powdery mildew, although the higher temps — above 70 — help stave off PM. I keep my flower room in 30s as much as possible, especially from midpoint on.

Are the higher temperatures a serious concern? I'm trying to figure out how to save money this summer, and the only way to prevent the mold at night is to run the dehumidifier a bit harder from 50% to 35-40%, however that's just going to put out more heat in my room. I can probably get the RH down to 35-40, but I see it getting up to 80-82F with the lights off.

Thoughts?

thats pretty high lights off temps. if your ac turns on when your lights come on, and lower the temps significantly, thats called a "cold air dump". flower growers do it for the first two hours of lights on, which causes very short internodal spacing (making for short, bushy plants).
i'd suggest leaving your ac on at night, but turning it down so the temps rise into the low 70s. it shouldn't take nearly as much energy with the lights off, you'd maintain a better differential, and a lower rh

Roger A. Shrubber said:

thats pretty high lights off temps. if your ac turns on when your lights come on, and lower the temps significantly, thats called a "cold air dump". flower growers do it for the first two hours of lights on, which causes very short internodal spacing (making for short, bushy plants).
i'd suggest leaving your ac on at night, but turning it down so the temps rise into the low 70s. it shouldn't take nearly as much energy with the lights off, you'd maintain a better differential, and a lower rh

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The ac and dehumidifier fight each other all night every couple of minutes. Once the ac reaches the target temperature, the compressor kicks off and it spits out air that's super wet and raises the RH to 99% within a minute or two.That's when the dehumidifier kicks on, corrects the RH, however it puts out enough heat to cause the AC to kick back on.. and it's like that all night for 12 hours straight.

I found a method that might work, and I wanted to give it a shot, but I needed to make sure that my environmental numbers are good enough.

Basically, I'll be opening my flower room door about half an inch, possibly all the way up to an inch, and then placing a weight behind it so that it cannot open any further.

When the AC is running, the negative pressure is enough to cause the door to close, and after the AC compressor stops running the door opens back up slightly.

That way when the lights and AC turn off for the day, the flowering room door pops open about an inch, and the fan and dehumidifier should be enough to move around air and keep the humidity in check.

In the morning when the lights and AC turn back on, the negative pressure closes the flowering room door, and it continues for the daily cycle.

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I've been trying to figure out a way to achieve this without getting a "smart vent" to open after lights off.

i know those vents exist, not sure what they cost. might be worth looking it up, if they're fairly cheap, would save a lot of tinkering

I like a 10 degree difference between night and day.
Can you run at night or perhaps use CO2 to increase your day time (lights on) temps?

Roger A. Shrubber said:

i know those vents exist, not sure what they cost. might be worth looking it up, if they're fairly cheap, would save a lot of tinkering

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I found a company that seems to sell a quality smart vent, and with a coupon they provided it was $154 shipped. However, then I would need a piece of ducting to fit that and lead to a 6" for my fan, add in a few timers and I'm looking at about $200. I don't really have that kind of extra cash right now, but I think I'm pretty close to tinkering my way into saving some money. I'd rather have the fan running and dehumidifier kicking on every 10-20 minutes for a couple minutes. I measured the dehumidifier running at 341 watts and the air conditioner running over 1,400 watts.. so choosing between the two I would much rather the dehumidifier. The only real problem being the heat created from the dehumidifier without the ac unit.. like I mentioned already it could possibly get up to 81F without the air conditioner at night. I just don't know if that's going to cause any issues.. there will be a fan big blowing across them during the night if that helps the situation.

Grandpapy said:

I like a 10 degree difference between night and day.
Can you run at night or perhaps use CO2 to increase your day time (lights on) temps?

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I don't think that I could run CO2 efficiently, as I probably have a lot more leaks than I think, especially with my portable ac unit, besides that's just another added expense at this point when I'm trying to save money. Typically throughout the rest of the year there's about a 10 degree difference between day and night, however we just rolled into summer and my basement is warmer.

JohnCee said:

I don't think that I could run CO2 efficiently, as I probably have a lot more leaks than I think, especially with my portable ac unit, besides that's just another added expense at this point when I'm trying to save money. Typically throughout the rest of the year there's about a 10 degree difference between day and night, however we just rolled into summer and my basement is warmer.

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$20 in co2 could save $100 depending on elec. costs. It's a lot easier for your ac to maintain 90-95 degrees.

Home depot about $75

My humidity was in the high 50s and low 60s for my flower. Not ideal by any means. Should be between 30-40. But I had a small fan going, and the front door and side vents open, and had no issues with pm or mold. Air flow did the trick for me.