What is a good hygrometer

I have like 3 hygrometers and not one says the same thing I think it’s time to get a couple good ones so what is everyone else using

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Hydrometer or hygrometer?

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Your right hygrometer meter

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How different are the readings from your different devices? Are they placed in the same location?

I use small hygrometers in my curing chambers, I have wireless “weather station” devices for random monitoring and I use temperature/rhumidity transmitters for the monitoring and control.

See below, @Drinkslinger posted links to two of the devices that I use as well.

I typically see values +/-5% which is about what the device specs claim. The transmitters that I use are the most accurate at +/-2%. These are made my Dwyer. You will need to have some sort of controller that accepts 0-10 V or 4-20 ma inputs to use these devices.

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I use these in my curing jars

These in my tents

Honestly, I’m not sure any of them are super accurate. I’m also not sure that my rh levels have to be spot on. I just need a general idea within ±5%

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There about 10% different in them

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I use the same ones in my jars and was just reading the acurite has got good reviews

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Well, this is not too unexpected as most of the commercial/retail devices only claim an accuracy of +/-3-5% which is a 6-10% range.

As an example, if the actual rH were 45%, you would expect to see values from most hygrometers in the range of 40% to 50%.

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I was also looking at something like this but how accurate are they https://www.amazon.com/Humidity-Controller-Inkbird-Humidistat-Pre-wired/dp/B01J1E5LWM/ref=asc_df_B01J1E5LWM/?tag=hyprod-20&linkCode=df0&hvadid=167130978684&hvpos=1o3&hvnetw=g&hvrand=3709257400062454426&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9017040&hvtargid=pla-314644480949&psc=1

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The rH spec on that controller is +/-3%. A range of 6%.

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The whole thing is that’s a lot of difference I got mold in my last grow and don’t want it again

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I don’t blame you there, mold is a big bummer!

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Ya want to get this under control before I start my grow this winter. I was also wondering y the intake fan. I have a good exhaust fan that has that good negative pressure with a 4” inlet. Shouldn’t it be pulling the air that is needed?

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“Pushing” air in is done to keep the negative pressure in the tent to a minimum. You want just enough negative pressure to keep air from leaking out (odor) plus, the more negative pressure you develop, the less air that is actually moving through the tent due to flow restriction.

I don’t use an inlet fan on my main room as I have plenty of air flow without it. I may end up using one in the new flower tent but not the veg tent.

The exhaust fan has several functions, the main one (for me anyway) is to cool the room and the other is to capture odor in the carbon filter. One other crucial role that the exhaust fan plays is replacing “used” air with fresh CO2 rich air.

Both of these functions rely on air movement. The negative pressure that we talk about is your assurance that odorous air is pulling through the filter rather than seeping out into the air outside the tent. That same negative pressure is an indication that less air is moving than would be possible with less flow restriction. More air flow implies better cooling potential (assuming the air outside the tent is cooler than inside the tent).

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But do you really need it with smaller grow tents I’m running a 32x32 veg tent and a 3x3 flower tent. I’m also running them in a series with a 6” connecting pipe. With my flower tent first then the veg tent has the filter.

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Whether you need an inlet fan or not depends upon your specific situation.

If you are able to keep your temperatures in the correct range with only the exhaust fan, then you are fine that way. That is how my main flower room is and how my veg tent is. Also, understand that cooling is not a huge concern for me with regard to the exhaust fan because I also run an A/C unit in each flowering space. During flower, when the dehumidifier is in operation most of the time, the exhaust fan can not keep up and the A/C unit kicks in.

In the veg tent there is much less heat so just the exhaust fan is sufficient.

With your exhaust fan running and your lights on, what is your maximum tent temperature?

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My tents run to colder the max 75 and it gets in to the 50’s at night in the winter I have to run a heater. I was thinking about making an environmental tent to help regulate what is going in the winter the humidity is also to low

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With low temperatures and low humidity, I would be trying to dial those in to the desired ranges for the phase of growth that your plants in in.

Personally, I got the temperature where I wanted it (75F - 82F) and then went to work on humidity which is heavily dependant upon growth phase, 70-80% seedling, 60-65% veg, 45-55% flower are my target numbers.

As for the mold, with good air flow, temperatures and humidity as stated, my main tool for keeping mold away (never have had a problem) is keeping the room clean. I have no exposure to outdoors and I disinfect with bleach water followed by clear water rinse followed with H2O2 water cleanse between grows.

I am not certain what other indoor growers do to keep mold away. Mostly I read about how they get rid of it after having a problem, which, as I understand it, is not always easy to do.

Here are a few tags of more experienced growers that may have better advice for you.
@Myfriendis410 @elheffe702 @Holmes @MacGyverStoner @Covertgrower
@Missiles @AAA @PurpNGold74 @blackthumbbetty @Bobbydigital

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I have a preference for SensorPush from amazon. Connects to your phone, and keeps a record of temperatures and humidity.

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The only thing I might suggest would be to use White Vinegar instead of bleach as it volatilizes away (acetic acid) much more quickly than bleach with less residue. Should be equally effective.

My feeling is that in my area, white powdery mildew is endemic so I treat as if I have it whether there are signs or not. Straight 3% peroxide (thanks @garrigan62!) does just fine for me and I incorporated that into my pest treatment too. The grow space I try to keep mechanically clean and like @merlin44 said; management of RH is important too. Although I like 25 or 30% for late flower for mildew prevention.

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