VPD Question

[Three Berries]

I agree there are extremes in nature but you can see why someone would question "optimal RH at 79%. It makes it tough on anyone trying to follow the science when the science seems questionable. At least from a laymans point of view.

I guess, why bother with the directions if everything is "general guidelines". Not a knock on you its on the VPD chart. I will take the time to look at few other VPD charts before I go getting all butt hurt about it .

I wonder how they grow outside in the desert?

 

[Three Berries]

This is the one I use and have been since the beginning. I do not particularly like the virtual one, as you have to continuously adjust the cross hairs. Maybe I am doing it wrong. It doesn't matter. I finish them off (last 3 weeks) @ 75 deg F and 55%. I dry 'em out @ 70 deg and 60% nice and slow.

I use the virtual one as a one of the home pages of my laptop. Then watch the two tents as the lights come on and heat up. Veg tent I keep OK with a wet towel hanging when light on and take it out and leave the door open a crack when lights off. The flower room with constant ventilation works great when lights out. Takes some babying as it starts up with a mister and a towel and it gets to temp. This is winter and maybe 72F for the highest temp, into the low 60fs lights out.

 

[f-e]

At 72 55 should really be enough. Though you can have condensation pouring down the walls and perhaps do better, until the environment goes funky.

You have plants, and a humidifier, so where is all the moisture going? A 600 and heaters. Is your extract system too strong? Could you tent the grow, and cool tube the 6 so it has it's own separate air supply to the tent.

 

[Three Berries]

It's interesting at lights off to see the air picking up vapor going through the tent, coming out higher humidity than what is going in. So transpiration is ongoing, something I was mistake with. Always figured no lights no worry about humidity.

 

[RockinRobot]

It's interesting at lights off to see the air picking up vapor going through the tent, coming out higher humidity than what is going in. So transpiration is ongoing, something I was mistake with. Always figured no lights no worry about humidity.

Lights off is when you have to pay attention to humidity most. Mold likes cool, dark and damp so keeping humidity low at night is important.

 

[f-e]

It's interesting at lights off to see the air picking up vapor going through the tent, coming out higher humidity than what is going in. So transpiration is ongoing, something I was mistake with. Always figured no lights no worry about humidity.

They drink about half as much at night, but this goes up with the amount of bud present. Maybe as much as 65% of the water consumption seen with the lights on.
RH, being relative, will rise simply because the temperature drops. Getting us closer to dew point.

 

[Three Berries]

Lights off is when you have to pay attention to humidity most. Mold likes cool, dark and damp so keeping humidity low at night is important.

The AC Infinity fans have a humidity sensor. Quick acting too. And can be programed to come on at a certain speed and level of temp or humidity. I was using this in the summer to limit the lights off to 75%.

 

[RockinRobot]

The AC Infinity fans have a humidity sensor. Quick acting too. And can be programed to come on at a certain speed and level of temp or humidity. I was using this in the summer to limit the lights off to 75%.

I prefer 50% or below for nighttime Rh

 

[hamstring]

Well thank you IC community for all the input and advice. I now have it where it will stay until the summer months. 72 deg @ 55% RH while the lights are on. Lights off I have a supplemental heater on and I am still maintaining 70 deg at 55% RH.

I am veging some small seedlings and I'm sure its a self-fullfilling prophecy but they seem to be growing at a faster rate already.

 

[Three Berries]

Got my AC Infinity 67 fan controllers today. It has Bluetooth and with their app I see they have a VPD leaf temp offset. So you can set it at a couple degrees under the actual air temp as it should be. Stepped ramp up speeds too with differential setpoints.

 

[flylowgethigh]

The controllers that came with my AC infinity T6 do not have a min speed they will maintain when they are on a humidity / temp control loop. So the fan can go off all the way.

I run the airflow at constant speeds now, and try to control the lung room.

 

[Three Berries]

It's the Cloudline 67 controller. If you just got one in the last couple of months they will give you a free upgrade. Otherwise you can buy the new controller for $50 I think. They just replaced two of mine for free.

 

[Three Berries]

With the cold temps I find that a low sped on the fan and humidity control worked great. The Veg tent is on and off for humidity control and the flower one is variable speed but a 1 speed as minimum. I think I can get it to switch programming a the light on/off time too if there is a need. Humidity control and temp control can be set individually and run concurrently. Minimum speed is easy to set. You can also set differentials for temp and humidity rise/fall so the fan will ramp up/down in steps if it can't keep things under control.

My first chart today. You can really see when the door gets opened......

 

[hamstring]

So does this thing have dry contacts turn on you fan and humidifier? If so $50.00 is a steal. Actually I need to control my heater not the fan . When the lights go out it can get down right cold in my grow room, below 60 deg F. I need it to maintain temp an RH. I'm not exhausting during veg cycle in the winter. No need to in my case.

Whoops, sorry about that it looks to only work infinity systems.

 

[Three Berries]

No aux outputs. You can run two AC Infinity Cloudline fans off one controller sharing the output,

Programming is pretty primitive. Using the humidity works great with lights off but lights on and it's temp that is what gets controlled unless you can really dump in some humidity.

So if you know what the peak temps will be during light off, you can set the humidity at that point and it ramps the fan on and off, unless the temp continues to rise. Also has a humidity offset where the fan will increase speed in steps if the humidly jumps more that the set points you set.

 

[Three Berries]

The scenario is lights on turn on a mister for the flower room tent and hang wet towels then use humidity control for the small tent. It has nothing but passive convective ventilation unless the fan comes on due to set points. Only 100w of lights for the moment. The flower tent has constant ventilation, the amount is regulated by the AC fan controller. But it runs best at a temp of around 74F. This allows the humidity to stay close to ideal depending on the house humidity.

A problem I have found is running the flower tent where the fan will cycle on and off, sometimes the draft blocker must stick shut and will need a good boost (speeds above 4) to pop it open. Keeping it at a minimum of 1 will prevent this. And the temp probe lead is too short if you want to mount it as far away as the power cords. You can use a 4 conductor 3.5mm M/F extension cord for the temp lead.

So my routine is at lights on the load up some towels with water. Depending on the house humidity and temp determines how many and how wet to keep them. I used a new timer last night and must not have set it right as I got up and no mister running. The VPD got into leaf curling damage zone over 1.6 most of the time.