RH fluctuations during light out.

[mafuhawkeestrees]

Hey, expanded my garden And running into so RH problems.

I have a 70 pint dehumidifier in a 12x6 flower room. I have 2 wall mounted oscillating fans. A 6in extraction fan and a 4 in scrubbing fan and a little portable heater in the room. I think this would be enough air movement in there? I do run a drain to waste and there is a bit of sitting water in the room at all times.

During lights out I have crazy RH fluctuations as show in pic. Worried about PM. How do I fix this? The dehumidifier is set to its lowest setting. Would a ink bird controller solve my problem?

 

[Redskare87]

So the extraction fan goes off at lights off? It looks like your humidifier is cycling and isn’t very accurate. Does the humidifier have a numerical set point for RH? I think if you had a humidifier outside the space that you could set a exact %humidity it would be more stable. Your numbers don’t look too crazy tho

 

[dbz]

Read this:

Why does my humidity spike at lights out?

I thought this would be helpful for some. Three things are at play, major factors anyways, aside from ambient humidity and whatnot. 1) Biomass - As the plants grow the amount of water respired is directly proportional to biomass. When the plants hit a certain size (I like to call it critical...

www.rollitup.org

Also, yes an inkbird controller would help a lot, turn the dehumidifier up all the way, and set a narrow band on the controller. The only thing you have to make sure of is that your dehumidifier has an auto start function. (If power loss happens and it regains power it turns back on automatically to last selected setting)

Although your humidity doesn't look that bad. Personally I would be shooting still for around 50. VPD and all.

 

[sf_frankie]

I'd be willing to bet its just your hygrometer being whacky with its readings. Humidity doesn't change that fast. See how there's a darkly shaded trend line in the middle of the graph? That is your actual humidity

edit: is that a govee thermometer? If it is, that is definitely what the problem is. I have the same one but I have a HomeAssistant integration that intercepts the temp/humidity broadcast and reports it on my dashboard. The integration smooths out the reading automatically before displaying on my dash board. First pic is the actual readings and second pic is with the graph smoothing.

 

[Rurumo]

Can't you just set a rh% target on your dehumidifier and it will just turn on until it hits that? Is the 70 pint just not keeping up?

 

[put1inthair]

wassup guys, i am a beginner so excuse my ignorance but if your r/h has a high of 52 why do u need a dehumidifier at all? except maybe at the end of flower in a humid area or something...?

 

[sf_frankie]

wassup guys, i am a beginner so excuse my ignorance but if your r/h has a high of 52 why do u need a dehumidifier at all? except maybe at the end of flower in a humid area or something...?

If it’s naturally that high you don’t. You can flower at 52% if you need to. It depends on your grow area. For instance, when my grow room is full of 50 mature plants in 5 gallon pots that are getting watered often, my RH will hit 80% without a dehumidifier. Some people can control humidity with extraction fans, some don’t need anything and some need multiple dehumidifiers. It all depends on your space.

 

[Beehive]

I use two ink birds. The secret to the ink bird is it has to be calibrated. Using the salt slurry method. They come from factory a few points off.

One controller is plugged into the light timer. It controls lights on RH.

The second controller is plugged into power strip. It maintains the night RH.


My plants have had a couple days of 70%+(It was raining). Most of the time, they've been around 55%-45%. Here lately the outdoor RH has been low. Currently at 26%. So I have the humidifier going. Usually after the morning water is when the plants themselves raise the RH. In my room it can reach 60%. At night, they sweat less so humidity isn't too big of problem at night.

The pain with a dehumidifier is it pumps hot air. It'll heat a bedroom to 80°+. Using it at night really keeps them warm.

 

[mafuhawkeestrees]

I'd be willing to bet its just your hygrometer being whacky with its readings. Humidity doesn't change that fast. See how there's a darkly shaded trend line in the middle of the graph? That is your actual humidity

edit: is that a govee thermometer? If it is, that is definitely what the problem is. I have the same one but I have a HomeAssistant integration that intercepts the temp/humidity broadcast and reports it on my dashboard. The integration smooths out the reading automatically before displaying on my dash board. First pic is the actual readings and second pic is with the graph smoothing.

View attachment 4814155
View attachment 4814156

Yes it is a grovee. Thank you for the reassurance!

 

[mafuhawkeestrees]

Can't you just set a rh% target on your dehumidifier and it will just turn on until it hits that? Is the 70 pint just not keeping up?

Set at 35%. It keeps up, just the Rh “spikes” 10-15% when it’s turning on and off. I understand that is breeding grounds for PM. Hoping to smooth out the fluctuations. Seems using a controller may help.

 

[mafuhawkeestrees]

If it’s naturally that high you don’t. You can flower at 52% if you need to. It depends on your grow area. For instance, when my grow room is full of 50 mature plants in 5 gallon pots that are getting watered often, my RH will hit 80% without a dehumidifier. Some people can control humidity with extraction fans, some don’t need anything and some need multiple dehumidifiers. It all depends on your space.

Well put. My RH naturally rises to around 80 as well. Dehumidifier is working, just don’t like the fluctuations.

 

[mafuhawkeestrees]

I use two ink birds. The secret to the ink bird is it has to be calibrated. Using the salt slurry method. They come from factory a few points off.

One controller is plugged into the light timer. It controls lights on RH.

The second controller is plugged into power strip. It maintains the night RH.


My plants have had a couple days of 70%+(It was raining). Most of the time, they've been around 55%-45%. Here lately the outdoor RH has been low. Currently at 26%. So I have the humidifier going. Usually after the morning water is when the plants themselves raise the RH. In my room it can reach 60%. At night, they sweat less so humidity isn't too big of problem at night.

The pain with a dehumidifier is it pumps hot air. It'll heat a bedroom to 80°+. Using it at night really keeps them warm.

Appreciate your response. Looking to get a few WiFi ink birds to help automate my room. Dialing in the ac/heater/dehumidifier with the control sets built in to the machines is proving difficult throughout season changes.

 

[sf_frankie]

Appreciate your response. Looking to get a few WiFi ink birds to help automate my room. Dialing in the ac/heater/dehumidifier with the control sets built in to the machines is proving difficult throughout season changes.

I don’t know how computer savvy you are but you can get a raspberry pi and run HomeAssistant on it. Home Assistant is an open source home automation platform that’s almost infinitely versatile depending on your skill level. There are enough community made integrations to run an entire grow room down to mixing nutes for you based on soil samples. For something that complex you’d need some serious python skills but the backbone is there. I don’t have any coding skills but I’ve managed to get pretty much everything automated. Light timer, humidifier, dehumidifier, video feed and ventilation. I even have it set up to calculate VPD in real time for me. I’ve also got a WiFi module on the way for my minisplit.

it’s definitely not beginner level stuff. I went in with minimal Linux experience but I’ve gotten a good grasp on it over the last few weeks. You should check it out. Apparently there’s a few threads on here for people who are using it, I just haven’t checked them out yet.

 

[mafuhawkeestrees]

I don’t know how computer savvy you are but you can get a raspberry pi and run HomeAssistant on it. Home Assistant is an open source home automation platform that’s almost infinitely versatile depending on your skill level. There are enough community made integrations to run an entire grow room down to mixing nutes for you based on soil samples. For something that complex you’d need some serious python skills but the backbone is there. I don’t have any coding skills but I’ve managed to get pretty much everything automated. Light timer, humidifier, dehumidifier, video feed and ventilation. I even have it set up to calculate VPD in real time for me. I’ve also got a WiFi module on the way for my minisplit.

it’s definitely not beginner level stuff. I went in with minimal Linux experience but I’ve gotten a good grasp on it over the last few weeks. You should check it out. Apparently there’s a few threads on here for people who are using it, I just haven’t checked them out yet.

I have a electronics degree so I’m familiar. Just a rabbit hole I don’t wanna go down right now lol. Appreciate the advice because that is the play if I wanted to spend another 500ish. I guess when I said automate my room I meant the minimum of the word.

 

[sf_frankie]

I have a electronics degree so I’m familiar. Just a rabbit hole I don’t wanna go down right now lol. Appreciate the advice because that is the play if I wanted to spend another 500ish. I guess when I said automate my room I meant the minimum of the word.

Yeah it’s definitely a rabbit hole! I’m only in it about $150 but I already had a bunch of smart plugs on hand along with the Govee thermometer so my costs were minimal. If I was working now I’m sure I’d be at least $500 in