Live Stoners Live Stoner Chat - Apr-Jun '23

[Hotfire]

See this is where i get confused..
According to the chart I'm in the danger zone but I don't know how to fix it if I'm supposed to keep humidity between 40 and 50 in flower.. I can't really get the temp down unless I turn the light down which will bring humidity up.

 

[Fermented_Fruitz]

Got you! i just dont know what to do sometimes when im at a temp and vpd that i dont see on the chart, like right now during the day my tent sits around 79 and 76 at night. so im probably just taking the chart too literal, since temp is something i have a harder time controlling vs humidity. this is my first grow with the controller 69 so before this i never knew vpd was even something i needed to pay attention to.

VPD Calculator

Solve For: Temp RH VPD Temp (F) Temp (C) RH (%) VPD Air (kPa) Leaf Offset (F) Leaf Offset (C) VPD Leaf (kPa)

pulsegrow.com

Using a calculator is super easy cuz u can set it to where u can enter your temp and vpd u want and it will tell u what humidity u need to accomplish this!

 

[Fermented_Fruitz]

See this is where i get confused..
According to the chart I'm in the danger zone but I don't know how to fix it if I'm supposed to keep humidity between 40 and 50 in flower.. I can't really get the temp down unless I turn the light down which will bring humidity up.
View attachment 1586817

Bro only time u leave it 40-50% in flower is if u ignore vpd altogether! Guesstimate u will prob need 50-55% with temp if 79 but use calculator it will tell u!

 

[Mara Cachafa]

Ignore charts and use a calculator! .8 for seedling/ 1.0 for veg/ and 1.5 for flower!

How do you calculate VPD with a calculator?

 

[Hotfire]

That’s where my tents hang around..Those temps should be on the chart little confused by that comment.. Same temp is what it is for the most part I can raise it by turning heaters on but can’t get mine lower which comes a issue during the summer.. So I run my night time during the day and lights on through the night to help compensate temps.. The controller 69 is great just set your high limits and turn the lows off.. Then I adjust the transition setting and my on and off speeds to fine tune everything

The chart you sent me goes from 75° to 77° and skips 76 . I'm just a perfectionist so it bugs me when my numbers don't match up now that I'm paying attention to vpd.

 

[Lil Dab]

See this is where i get confused..
According to the chart I'm in the danger zone but I don't know how to fix it if I'm supposed to keep humidity between 40 and 50 in flower.. I can't really get the temp down unless I turn the light down which will bring humidity up.
View attachment 1586817

I’ve noticed that my controllers VPD calculation doesn’t match the charts If I’m looking at that right you are lower then 1.6 vpd

 

[Lil Dab]

The chart you sent me goes from 75° to 77° and skips 76 . I'm just a perfectionist so it bugs me when my numbers don't match up now that I'm paying attention to vpd.

Just spilt the difference it shouldn’t make that big of deal everything is fluctuating so that could go both ways a little bit IMO

 

[Fermented_Fruitz]

How do you calculate VPD with a calculator?

Go to that link! It asks for your temp and rh and will tell u vpd! Or u enter vpd u want and temp or rh and it will tell u what other needs to be set at to accomplish it!

 

[Lil Dab]

@Hotfire I have multiple temp and rh monitors and all will give a me different vpd number slightly I just go by the average

 

[Mara Cachafa]

Go to that link! It asks for your temp and rh and will tell u vpd! Or u enter vpd u want and temp or rh and it will tell u what other needs to be set at to accomplish it!

Oh, OK, thanks! I thought you meant find my old Texas Instruments solar calculator and figger it out.