Weird temperature issue

[Fish scale]

So I'm growing some seedlings, they are a few days old and my inkbird temperature gauge says the temperature is 20c but my hygrometer says the temperature is 23c and I'm not sure which temperature gauge is right. I know 20c is a bit cold for seedlings and I want the temperature to be around 23-24c and I'm a bit confused about the different readings. Should I buy another hygrometer just to be on the safe side? And if the new hygrometer reads 23-24c then carry as normal? My inkbird temperature gauge is pretty old. It's about 4 or 5 years old so I'm guessing it might be out of calibration? or maybe the hygrometer is reading wrong instead of the inkbird? Any help would be appreciated.

 

[Phytoplankton]

I would tend to believe the inkbird more than the hydrometer, but if as you say, the inkbird is older it could be out of calibration (is there a way to calibrate it?) I think getting a "third opinion" (another hydrometer) is your best option. I have some of the same hydrometers and have seen variations of 2-5 degrees F between different ones side by side.

 

[Fish scale]

I would tend to believe the inkbird more than the hydrometer, but if as you say, the inkbird is older it could be out of calibration (is there a way to calibrate it?) I think getting a "third opinion" (another hydrometer) is your best option. I have some of the same hydrometers and have seen variations of 2-5 degrees F between different ones side by side.

I don't think there is a way to calibrate the inkbird temperature gauges but I could be wrong. I will order another hygrometer and see how I get on. hopefully the new hygrometer will read 23 - 24c and then I won't need to use my tubular heater. I might buy another inkbird temperature guage too just to make sure I am getting the right readings. I will keep you updated

 

[Jjgrow420]

You can def calibrate inkbird controllers. The setting is cal +- when going through the setting prompt.
Diff areas of the tent will read diff temps. Those cheaper style units are notorious for being (+-) 3-5° id check the instructions and see how accurate it is.

 

[BigGreenThumb]

I’d buy another hygrometer since they are cheap enough. Place both new and original hygrometers next to the temp probe for your Inkbird. Monitor it for a couple of days and then calibrate the inkbird accordingly. You should find calibration settings when you scroll through the menus

 

[coreywebster]

1. Those cheap hygrometers have a wide range of accuracy , as in they're not.
2. It depends where you place them.
If you're going to put it in direct light then the large plastic object is going to be thrown off more than the small sensor.
The bigger surface will warm up more and throw off the real reading

 

[Jimski]

The inkbird I had could adjust offset. The setup is a pain with the icons looking alike but just count the button pushes to the correct pid.
Now about sensor drift and calibration.
How many people zero point a pH meter? How many zero point an EC meter? Then why o why do I almost never hear about zero point on temp and humidity sensors?

My version of zero point day has me put all sensors including a very accurate capillary temp gauge and zero them all to the same reading.
In addition I recommend

Amazon.com

This 3 pack Bluetooth sensors are my backup plan for when power goes out. The ACI and Vivosun apps require a connection to the internet and when the network drops you need to read the controllers for info. I just connect to the free app and can read from upstairs temp and humidity. The 3 pack sensors are also great as you can move them around in the tent and find dead air in your grow by these sensors.

Last thing. If you look at the sensor specs for all manufacturers ACI Vivosun inkbird they all list specs on accuracy. None of them list precision and there is a difference. Accuracy determine how close each measurement is for multiple readings. Precision is how close to ACTUAL readings your data is. Most state on the box 1 or 2% +- for temp and as high as 4% +-on humidity. This is a large variance and if you take a look at a vdp chart look where your numbers are if your temp is off 2 degrees.

In addition you will also need to deal with sensor drift. I have no shit 6 temp and humidity sensors in my small tent. The main canopy assembly has 3 ACi sensors and 1 Vivosun sensor as well as one growee sensor. The other 2 growee sensors I move around looking for air not moving. I was very surprised how moving the incoming duct air hose placement affected the swirl of fans. Moving just a foot or directing the air the wrong way caused humidity dead spots where it would be 5% higher or lower than a space 2 feet away. After much testing I found that duct settings for my tent needed to be at least setting 5 or the air did not move properly and evenly.

Inkbird sensors are Kool but the accuracy of the sensors was not the problem. Using it to turn a humidifier or dehumidifier off and on results in poor control. The humidifier had a spool up and run down effect that gave me a 3% up and down from settings window that was not real useful for humidity control.

 

[Fordprefect42]

Ive generally broken the tie by taking the inkbird or whatever you are using outside for awhile, and matching up the temperature it reports with the official outdoor temperature.

 

[Delps8]

I wouldn't worry about the thermometer or the hygrometer just now. I'd pay a lot of attention to the thermostat.

23° is very cold for most plants, cannabis is no exception.

This chart is from "Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions", the primary author being Suman Chandra.

While the focus of the paper is on cannabis' response to different values of CO2 and PPFD, it illustrates the rate of net photosynthesis at different temperatures, as well.

At 20°, the plants were generating about 7 units of net photosynthesis. When the ambient temperature was raised to 25°, that rate doubled (±).

(net photosynthesis is not a valid proxy for crop yield but it is a valid proxy for growth.)



My practice has been to grow, through early veg, with temps in the low 80's during lights on.

 

[Fish scale]

I wouldn't worry about the thermometer or the hygrometer just now. I'd pay a lot of attention to the thermostat.

23° is very cold for most plants, cannabis is no exception.

This chart is from "Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions", the primary author being Suman Chandra.

While the focus of the paper is on cannabis' response to different values of CO2 and PPFD, it illustrates the rate of net photosynthesis at different temperatures, as well.

At 20°, the plants were generating about 7 units of net photosynthesis. When the ambient temperature was raised to 25°, that rate doubled (±).

(net photosynthesis is not a valid proxy for crop yield but it is a valid proxy for growth.)
View attachment 5453449


My practice has been to grow, through early veg, with temps in the low 80's during lights on.

I bought another hygrometer and they are both reading 24 - 25c so I calibrated my inkbird from 20c to 25c since both of the hygometers were reading 25c. My inkbird thermostat is about 5 years old so I think it wasn't calibrated properly. But I could be wrong? My seedlings are sitting around 24 - 25c according to the hygrometers. And the hygrometers are both brand new.

 

[Fish scale]

I would tend to believe the inkbird more than the hydrometer, but if as you say, the inkbird is older it could be out of calibration (is there a way to calibrate it?) I think getting a "third opinion" (another hydrometer) is your best option. I have some of the same hydrometers and have seen variations of 2-5 degrees F between different ones side by side.

I got another hygrometer and they are both reading 24 - 25c and they are brand new hygrometers. the inkbird is 5 years old so I'm guessing it just needed calibrating?

 

[1212ham]

Cheap hydrometer/thermometers can have poor humidity accuracy and slow response time but digital temp measurements are usually very accurate, within less than .5 C in my experience. A large unit can be respond slowly to temp changes but small probes are much faster since they have little mass.

As mentioned, a large thermometer can be heated by direct light since it has more area to absorb radiant heat. To compare temp probes I tape them together or use a twist tie.

 

[Fish scale]

Cheap hydrometer/thermometers can have poor humidity accuracy and slow response time but digital temp measurements are usually very accurate, within less than .5 C in my experience. A large unit can be respond slowly to temp changes but small probes are much faster since they have little mass.

As mentioned, a large thermometer can be heated by direct light since it has more area to absorb radiant heat. To compare temp probes I tape them together or use a twist tie.

So the chances are my inkbird thermometer is reading right and it’s only 22c in my tent right now instead of 25c like the hygrometers say? Because if the hygrometers are right and it’s actually 25c I don’t want to increase the temperature and nuke my seedlings with too much heat.

 

[Jimski]

So the chances are my inkbird thermometer is reading right and it’s only 22c in my tent right now instead of 25c like the hygrometers say? Because if the hygrometers are right and it’s actually 25c I don’t want to increase the temperature and nuke my seedlings with too much heat.

The broad range of temps for seedling 68-77 or 20-25 c means you are not going to nuke your plants if you stay in the lane.
If your temp is not accurate set temp at 22.5 c. You can be off by 2 c and still be in the lane.
Gunna be ok. Once you have some growth get some heat on em. I ran most of veg at 82-85 or 27-29c but in flower I would recommend a more accurate master temp to zero your system as the trend for flower in cannabis is lower temps to get the plants to stack resins and get more bag appeal with color expression.

 

[Delps8]

So the chances are my inkbird thermometer is reading right and it’s only 22c in my tent right now instead of 25c like the hygrometers say? Because if the hygrometers are right and it’s actually 25c I don’t want to increase the temperature and nuke my seedlings with too much heat.

25°C is a good temperature for the later part of flower but at 25°, your plants will grow more slowly than they will at 26, 27, 28 etc up to about 38°.

The main reason for the temperature limit is that, as temperature increases, transpiration increases and, if a soil grower isn't careful, the plant may not be taking up enough water to keep up with amount of water that's being transpired out.

I germinate at "80 and 80" and allow the temp to rise to 85°± until the second week in flower. I use those temperatures based on experience and research. The most cogent advice I've seen about getting the most out of your cannabis crop is the video whose title is in the graphic below.

The video is best I've seen in the many hundreds of hours I've spent learning about growing cannabis and I recommend to every grower.



I've added the chart below because it shows the impact of temperature on net photosynthesis ("net P"). If you follow the 500µmol line, you'll see that net P is about 7 units at 20, 14 units at 25 and 18 units at 30.

 

[Delps8]

I bought another hygrometer and they are both reading 24 - 25c so I calibrated my inkbird from 20c to 25c since both of the hygometers were reading 25c. My inkbird thermostat is about 5 years old so I think it wasn't calibrated properly. But I could be wrong? My seedlings are sitting around 24 - 25c according to the hygrometers. And the hygrometers are both brand new.

It's not easy to get an accurate RH reading in a grow tent using consumer devices. Temperature is easy, though.

Head over to YouTube and look up "the salt method" for calibrating hygrometers and that will get you to 75%.