# RH soars when lights go off

**URL:** <https://ilgmforum.com/t/rh-soars-when-lights-go-off/31521>\
**Category:** Autoflowers\
**Created:** [May 26, 2019, 5:14pm UTC](https://ilgmforum.com/t/rh-soars-when-lights-go-off/31521 "2019-05-26T17:14:16Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Carol4486](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/carol4486/32/246517_2.png) [@Carol4486](https://ilgmforum.com/u/Carol4486)\
**Post date:** [May 26, 2019, 5:14pm UTC](https://ilgmforum.com/t/rh-soars-when-lights-go-off/31521/1 "2019-05-26T17:14:16Z")

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Every time my lights go out my RH goes from 50ish to 68 in less than an hour. What can I do besides install dehumidifier? They are flowering and I don’t want mold. I have a small fan in center of them blowing up and a oscillating fan working the branches. I’ve tried with exhaust off no help exhaust on no help

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**Author:** ![WickedAle](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/wickedale/32/137618_2.png) [@WickedAle](https://ilgmforum.com/u/WickedAle)\
**Post date:** [May 26, 2019, 5:27pm UTC](https://ilgmforum.com/t/rh-soars-when-lights-go-off/31521/2 "2019-05-26T17:27:31Z")

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Your leaves are perspiring and your lights aren’t burning it off. You hygrometer is probably close to the plant so you have a microclimate of high humidity around the plant. More ventilation and air flow even when lights are off will lower the humidity around the plants.

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**Author:** ![Carol4486](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/carol4486/32/246517_2.png) [@Carol4486](https://ilgmforum.com/u/Carol4486)\
**Post date:** [May 26, 2019, 5:29pm UTC](https://ilgmforum.com/t/rh-soars-when-lights-go-off/31521/3 "2019-05-26T17:29:35Z")

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So should I be worried? I am flowering almost 5 weeks in. It’s a 4 hour lights out. I have a intake fan that I usually don’t use because it causes tent to pillow but I think I’ll program that to turn on when lights go out. Do you think that will help? Should I move the hygrometer? It’s in the canopy

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**Author:** ![HornHead](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/hornhead/32/267986_2.png) [@HornHead](https://ilgmforum.com/u/HornHead)\
**Post date:** [May 26, 2019, 5:40pm UTC](https://ilgmforum.com/t/rh-soars-when-lights-go-off/31521/4 "2019-05-26T17:40:50Z")

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Run your exhaust fan always. Itll keep new air moving and lower humidity

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**Author:** ![tanlover442](https://avatars.discourse-cdn.com/v4/letter/t/7ba0ec/32.png) [@tanlover442](https://ilgmforum.com/u/tanlover442)\
**Post date:** [May 27, 2019, 12:18am UTC](https://ilgmforum.com/t/rh-soars-when-lights-go-off/31521/5 "2019-05-27T00:18:58Z")

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suggest you set intake and exhaust fans to run for an hour after lights out.

you could also open the sides if you have a tent or screen…