Inkbird Environment Control Automation - VPD Made Easy!

[NezA]

3 hours ago, superfruit said:

@mikeydoughnut @NezA are you guys using heat mats while chasing the VPD dragon? My roots are always 24c or so, but I'd assume VPD is still totally applicable and maybe even unchanged by this due to the fact that the variables are leaf temp, environmental temp and rh.

 

To be honest mate I find if my ambient is at the right level my root zone is generally fine. I did have some tube heaters in there but they've been commandeered for the veg tent 

[Bush Cat]

I'm running 2 mats and and an Inkbird set at 22 -24 do you think it would be better if the numbers were closer? 

[Shumroom]

@BUSHCAT just set the temperature you want,

lets say 23C for argument sake.

 

Next reduce the coolback and hysteresis settings to 0.5C or closer if you choose.

 

Hope this helps.

 

Atb

 

 

[superfruit]

Found an interesting video on calibration of these Inkbird devices: youtube.com/watch?v=AI9jC_wXd1k

[NezA]

@mikeydoughnut yeah mate my mix is compost, earthworm castings and perlite. I do use organic nutes at the moment, but I think I'll switch to salt based nutes for the blumats by all accounts they don't cope with organic nutes at all well. I'm switching nutes for the next run but haven't quite decided yet. I'm definitely going to give Intense Nutrients a bash, for blumats I'll go with their Dirt range.

 

But then again I might give the Organix range a bash and handwater one more run...

 

Eventually I'm switching to living soil so the blumats will only be running plain water then. This run I just finished, the feed issues really got me down, so I need to change something, but haven't decided exactly what's changing yet though.

[superfruit]

My Inkbirds arrived, and I actually stumbled across an interesting post at cannabisbusinesstimes.com/article/cbt-032316-led-transition-lighting-testing which quotes:

 

Quote

The actual temperature is very cultivar-dependent, but the ambient air temperature with LED lighting runs generally about 10 degrees cooler than other systems, says Ryall. Under HPS, growers aim for a 75-degree air temperature, which puts the leaf surface temperature at about 85 to 88 degrees. Since LED lighting runs cooler, he’s seen the best results by raising the ambient air temperature by about 10 degrees. Ryall likes to see that number at about 82-85 degrees, which will make a lot of growers “fall out of their chair,” he says. It might actually mean bringing the temperature of the grow area up a little to the best range for the plant.

 

So in my case using HPS no way am I going to have a -2c leaf temp difference, but more like a +x difference which to me makes total sense as the environment source of heat is the HPS lamp itself. At least, this is the case during the light cycle. When lights are out the oil rad will kick in, and therefore leaf temps will likely drop to -x instead. Probably +5.5c leaf temp which breaks the charts

 

Seems I have some calculations to do, and will need an IR thermometer sooner rather than later.

 

Another of interest: 

Edit: Wow, loads of resources discussing hps and leaf temps. I need to do some reading!

Edited January 21, 2021 by Joolz
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[growinggold]

Remember chaps vpd is mainly relevant with lights on when the plants have there stomata open. Think that's what the pulse grow email said. 

[superfruit]

Just now, growinggold said:

Remember chaps vpd is mainly relevant with lights on when the plants have there stomata open. Think that's what the pulse grow email said. 

 

That definitely makes night-time calcs easier. But using HPS seems to cause VPD upsets.. hmm

[growinggold]

@superfruit I'm still trying to get my head around it myself tbh. Im going to do a diary update tonight and will include a vpd section as I've noticed one my sensors now includes this so I will post my findings for different leaf temprattue off sets (-1 and -2) and show you the vpd over typical lights on 12 hours period. 

 

I don't have a infra red sensor so again it's little guess work but you all may find interesting. Has any one taken a infrared reading for led environment here yet?

[Bush Cat]

4 hours ago, Shumroom said:

@BUSHCAT just set the temperature you want,

lets say 23C for argument sake.

 

Next reduce the coolback and hysteresis settings to 0.5C or closer if you choose.

 

Hope this helps.

 

Atb

 

 

Cheers bud, I'll have look, I managed to get the controller that switches from heating to cooling for £21 from Bezos on a deal

[superfruit]

@growinggold thanks mate. Are you using LED?

[growinggold]

Yeah I'm running 150w scope v2 led and 220w highlight led in a 80x80cm

[superfruit]

Should be fairly easy for you to manage VPD then as your leaf temps will be sensible. Due to using HPS I think my leaf temp will probably be significantly higher than the room temp and will throw those charts out the window. If you try changing the chart to +5c leaf temp then there leaves no green zones. Something feels off here.

 

If i'm understanding this correctly I probably want to be targeting an ambient temperature of around 23c where possible, to help keep leaf temperature down a little while under the HPS.

 

Into the rabbit hole I go: dammit @NezA why did you have to tempt me into this fancy tech haha

Edited January 21, 2021 by superfruit

[growinggold]

I think you maybe be being a bit hasty with your temps. I get that hps is hotter but surly Its +2 rather then -2 give the 4c difference. +5 seems an awful lot. 

[superfruit]

At the moment @growinggold I'm only going by what these websites state - a +10f difference, which is 5c I think. I guess here's why it's important to have good airflow around them.

Edited January 21, 2021 by superfruit