HUMIDITY AT NIGHT? TO PREVENT MOLD

Flowki

Flowki

Well-Known Member
Cinco said:
There are a lot of mold resistant strains. You can look them up. Many commercially developed and viable strains are mold and PM resistant. Resistant being the key, nothing is mold proof.

I have done runs at peak flower VPD at 80% RH and not had any rot issues. Plants love it. But I use multiple fans blowing under and through the canopy. Not just a gentle breeze, on max blowing air through the canopy. What most people would call too much airflow, probably. Never an issue on my end.

Where people have issues, in my pure opinion anyway, is with big swings as @Renfro said. 30c and 80% RH runs great if you maintain it... the plants grow like you would expect they would in a lush tropical equatorial rain forest.

However, like running anything at its max, there is less margin for error — when the temp swings down at lights out, you hit the dew point very quickly. At those room specs (30c, 80% RH)the dew point is only 26.2c. Only 3.8 degrees margin, or 12.6% temperature delta — , and below that, and all that moisture starts crashing out of the air and accumulating on the surfaces of everything. PM and mold love it.

So maintaining roughly the same vPD at a lower temp provides better buffer. At 20c and 60% RH, for example, the dew point is at 12c. 8c difference, and a much bigger margin at 40% delta needed to hit the dew point.

Just my thoughts from years of growing things, most of it not weed.
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So it would it be a good idea to have individual lights turn off in 10 min intervals, to allow out take to cut off and heater to regain some temp and avoid potential due point?.

Btw is a lights on RH swing of 70% down to 62% over roughly a 10 min cycle too much?. Out take kicks in at 79f but it spikes to 80 as the out-take is set very low for a gradual reduction (depends on outside temps ofc). The RH inadvertently drops to low 60's but I dunno if it's enough or often enough to justify humidification at that kind of interval?. Rh rises quickly once low temp is reached and out take shuts off. The dehuey is on a 5 min protection from the inkbird.

The de-huey is set to 65% and the peak rh goes to 70%. I'm half wondering if I should just let the room naturally settle at it's own upper RH and have the humidification kick in with the outake to keep humidity up in the 72-75% range during that out take period?. It seems like I am fighting the respiration atm.
 
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Star Dog

Star Dog

Well-Known Member
Cinco said:
There are a lot of mold resistant strains. You can look them up. Many commercially developed and viable strains are mold and PM resistant. Resistant being the key, nothing is mold proof.

I have done runs at peak flower VPD at 80% RH and not had any rot issues. Plants love it. But I use multiple fans blowing under and through the canopy. Not just a gentle breeze, on max blowing air through the canopy. What most people would call too much airflow, probably. Never an issue on my end.

Where people have issues, in my pure opinion anyway, is with big swings as @Renfro said. 30c and 80% RH runs great if you maintain it... the plants grow like you would expect they would in a lush tropical equatorial rain forest.

However, like running anything at its max, there is less margin for error — when the temp swings down at lights out, you hit the dew point very quickly. At those room specs (30c, 80% RH)the dew point is only 26.2c. Only 3.8 degrees margin, or 12.6% temperature delta — below that, and all that moisture starts crashing out of the air and accumulating on the surfaces of everything. PM and mold love it.

So maintaining roughly the same vPD at a lower temp provides better buffer. At 20c and 60% RH, for example, the dew point is at 12c. 8c difference, and a much bigger margin at 40% delta needed to hit the dew point.

Just my thoughts from years of growing things, most of it not weed.
Click to expand...
Have I got this right, the dew point is predictable relative to the heat and humidity your room is at?
My room is 50/52% 26.3c at canopy level and 24.5c under it what should be my maximum rh% to prevent dew at light out?
I've got a bit of scope with my temps and humidity, any constructive comments or advice welcome?

Fwiw I'm programed to be concerned about dark rh% above 60%

Cheers SD
 
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