do c02 levels need to come down during night hours (while flowering)

ttystikk

Well-Known Member
Thats awesome bro!!! Congrats on the sealed room. No tricks really, just make sure you can control your rh during the lights off period. I too do the last to weeks at 350, however I'm at 900ppm from week one till then. As far as how its been going, co2 enrichment is a whole other world. Explosive growth, bigger yields, everything you've heard is true. It did take me a few runs and many sleepless nights to dial it in though.
I'm finishing up the installation of a 5 Ton heat pump, which will both cool my op and provide heat for effective nighttime dehuey... FREE. After all, I've already paid for that heat once and then paid again to move it out of my grow- why waste it? In addition to dehuey, the excess heat will warm my home, heat my domestic hot water, heat my garage, my hot tub and even my driveway when I get it repoured. FREE!

I'll finally be able to run my grows fully sealed- and of course that means CO² supplementation as well! You mentioned some sleepless nights dialing things in with CO². Can you tell me what to look for and how you dealt with it?
 

hotrodharley

Well-Known Member
I'm finishing up the installation of a 5 Ton heat pump, which will both cool my op and provide heat for effective nighttime dehuey... FREE. After all, I've already paid for that heat once and then paid again to move it out of my grow- why waste it? In addition to dehuey, the excess heat will warm my home, heat my domestic hot water, heat my garage, my hot tub and even my driveway when I get it repoured. FREE!

I'll finally be able to run my grows fully sealed- and of course that means CO² supplementation as well! You mentioned some sleepless nights dialing things in with CO². Can you tell me what to look for and how you dealt with it?
Look into bottom heating indoor grows using the heat pump. Extremely vigorous root development and allows you to keep the room air cooler and makes tighter buds.
 

a mongo frog

Well-Known Member
I'm finishing up the installation of a 5 Ton heat pump, which will both cool my op and provide heat for effective nighttime dehuey... FREE. After all, I've already paid for that heat once and then paid again to move it out of my grow- why waste it? In addition to dehuey, the excess heat will warm my home, heat my domestic hot water, heat my garage, my hot tub and even my driveway when I get it repoured. FREE!

I'll finally be able to run my grows fully sealed- and of course that means CO² supplementation as well! You mentioned some sleepless nights dialing things in with CO². Can you tell me what to look for and how you dealt with it?
So iam burning with an 8 burner. I was watching for temps. I researched but not enough back then. So i ended up buying a 3 ton. I noticed a lot of twisting of leafs at first and frying of some leafs. So i did more research and figured it must of been from vpd (water around the leafs is what i took from it). Got a second dehue and kept temps 80-81 with around 900-1000 ppm. never over 1000. Lights off RH i wasn't ready for, think cuz of the massive amount of co2 they take in the transpire rate in the night cycle is huge. This is all stuff i just did and felt comfortable with. Many others are killing it with 1500ppm with high temps and high RH. Iam just scared to bring temps and RH that high.
 

ttystikk

Well-Known Member
So iam burning with an 8 burner. I was watching for temps. I researched but not enough back then. So i ended up buying a 3 ton. I noticed a lot of twisting of leafs at first and frying of some leafs. So i did more research and figured it must of been from vpd (water around the leafs is what i took from it). Got a second dehue and kept temps 80-81 with around 900-1000 ppm. never over 1000. Lights off RH i wasn't ready for, think cuz of the massive amount of co2 they take in the transpire rate in the night cycle is huge. This is all stuff i just did and felt comfortable with. Many others are killing it with 1500ppm with high temps and high RH. Iam just scared to bring temps and RH that high.
I'm going to run 1500ppm and RH in the high sixties, day and night. You see, it's usually not so much about the plant's transpiring water all night as it is about the cooling system bringing the nighttime temps down, driving RH up. You need heat overnight to keep that from happening, and that's what will keep your plants healthy while you feed them massive doses of CO².
 

a mongo frog

Well-Known Member
I'm going to run 1500ppm and RH in the high sixties, day and night. You see, it's usually not so much about the plant's transpiring water all night as it is about the cooling system bringing the nighttime temps down, driving RH up. You need heat overnight to keep that from happening, and that's what will keep your plants healthy while you feed them massive doses of CO².
Sounds like you got it down. What temps are you thinking of running?
 

ttystikk

Well-Known Member
Sounds like you got it down. What temps are you thinking of running?
81 daytime, 75 nighttime. Water cooled air handlers will run on high for cooling and low for dehuey. Whenever temps fall below 75 the baseboard heaters will kick on. This keeps temperature up and thus RH down.

I'm aiming for RH in the sixties day and night to help the plant absorb as much additional CO² as possible. Keeping RH stable day and night will also keep powdery mildew at bay.
 

Budley Doright

Well-Known Member
Tty just wondering if the relative humidity is all that important of a reading as it doesn't really give you the moisture content, just how much the the air can hold at that temp. Always been curious about that but never gave it much thought. I guess at normal grow room temps it's kind of a good guide line but still. Don't mind me, got a bag of sativa so been thinking lots lol.
 

ttystikk

Well-Known Member
Tty just wondering if the relative humidity is all that important of a reading as it doesn't really give you the moisture content, just how much the the air can hold at that temp. Always been curious about that but never gave it much thought. I guess at normal grow room temps it's kind of a good guide line but still. Don't mind me, got a bag of sativa so been thinking lots lol.
Well it's a good question. Here's how it works; what's important to the plants about moisture in the air isn't how much there is, it's how it is interacting with the plants. That's why ideal ranges for RH vary by temperature. See VPD = Vapor Pressure Differential.

The actual quantity of airborne moisture comes into play when temperature falls, like after your lights shut off for the day. As temperature falls, if nothing is done about RH, it will rise precipitously and create all sorts of problems. Yet attacking it directly with condensation coils like in an AC unit can be counterproductive, because the unit might drag the room temperature down with it and maintain high RH even while it removes excess moisture. This defeats the purpose! So what to do?

Add heat. It's that simple; after lights out, add some heat for your dehuey system to work against, and voila! Problem solved!

Adding heat will keep RH down and stable and will promote healthy crops.

Here's a VPD chart;
downloadfile.jpeg
 

WestDenverPioneer

Well-Known Member
I supplement with CO2 at all plant stages.
I never supplement at night.
Tittysticks method is to avoid the dew point and that's why he heats at night just enough to keep it healthy. A lot of people run into problems when they supplement with CO2 because it causes a lot of other variables to act up differently, or to an extreme level that the plant no longer tolerates the environment. You can have so much water vapor in the air that when your room cools your leaves become wet from condensation creating a ripe breeding ground for many bad things.
CO2 in a closed environment is a very advanced technique. It can be very good or it can be very bad. Just like nitrous in an engine, you can blow up a crop with CO2. I go through a ton of gas and I don't care. I also drive a 4x4 with a big motor and it uses a lot of gas too. CO2 is cheap. I don't care. Gas on. Giddyup.
 

ttystikk

Well-Known Member
I don't think I could achieve 75% in Denver even with a shower in the room open and running.
Highs in the Mid 60%'s work well for me, Lows in the 50%'s. Feels like the tropics compared to regular Colorado air.
I see your fifty percent and raise you as high as you want, brother. I got those RH levels, no problem; but then I have massive humidification... the plants themselves.
 

DemonTrich

Well-Known Member
great thread. about to enter the sealed room, dual hose a/c, deheuy, co2 and blueprint dbac2 with fuzzy logic phase of my grow this coming flip in 1 week. big step, and hoping for big returns as well.

bad ass controller, unfortunately only my a/c and co2 will be plugged into it (14A max inputs). the deheuy on its own and will use its onboard functions for on/off.

im not sure ill worry about VDP in flower. been running 75* and 55% for 3 yrs now with great results. my veg room is another story, 82* and 75% thanks to my 9 disc ultrasonic fogger.
 

since1991

Well-Known Member
All in one controllers are largely unnecessary. You will find that a good dehuey and mini split work better using the built in humidistat and thermostat. Save your cash and buy the digital co2 ppm controller/sniffer on its own. I know of many sealed room growers that bought the all in ones with relays and eventually end up using the ppm sniffer part only. Myself included. Its actually not good to hook up dehueys and minis to the co troller with relays. They cycle the compressor to often leading to premature burn out. It doesnt happen all the time but can happen. Any real pro grower with a sealed room with industrial dehuey (santa fe) and a nice mini split will tell you skip hooking the appliances up to a controller. Using the built in stats in the units themselves is much much better. Take it from someonr who speaks from experience.
 

ttystikk

Well-Known Member
All in one controllers are largely unnecessary. You will find that a good dehuey and mini split work better using the built in humidistat and thermostat. Save your cash and buy the digital co2 ppm controller/sniffer on its own. I know of many sealed room growers that bought the all in ones with relays and eventually end up using the ppm sniffer part only. Myself included. Its actually not good to hook up dehueys and minis to the co troller with relays. They cycle the compressor to often leading to premature burn out. It doesnt happen all the time but can happen. Any real pro grower with a sealed room with industrial dehuey (santa fe) and a nice mini split will tell you skip hooking the appliances up to a controller. Using the built in stats in the units themselves is much much better. Take it from someonr who speaks from experience.
Sorry, I've been there and done that and my experience has not always supported your strategy. This is home turf for me and I (respectfully) disagree;

Minisplits are fine for home and shop use, but once you get big you need real deal HVAC tonnage.

An all in one controller can work brilliantly as long as it's set up properly. The excessive cycling you mention is an easy problem to fix; just widen the cooling temperature spread, aka increase rise on the controller.

That said, I do advocate that people get individual devices because if an all in one breaks, you're at zero.

The only time it makes sense to use the device's own thermostat is when it's in the area it's supposed to control. Again, past a certain scale, hanging AC units all over the place becomes a loser's game very quickly. What's needed is remote HVAC with at site air handling, and that means water lines and water cooled air handlers.

A permanent facility- like a home, greenhouse or production facility- can greatly improve its performance and efficiency by installing a water based HVAC system. A chiller or heat pump rejects heat from the cold circuit and pumps the heat to the hot circuit. Cold circuit services WCAH- water cooler air handlers, that simultaneously cool and dehumidify the space.

Also, as facilities get larger it only makes sense to have several environmental sensors scattered about to keep various zones in the right conditions. This necessarily means a larger, distributed monitoring and control system and again, not from the front of the box.

Hot circuit picks up the heat rejected by the heat pump and can heat the house/facility and do many other useful power and thus money saving chores. This boosts efficiency and effectiveness substantially as scale increases, directly reducing operating costs and therefore increasing profits.

I've installed a heat pump in my home and it will heat my house and my domestic hot water with heat rejected from my grow. When's the last time you calculated a return on investment for YOUR furnace?!
 

since1991

Well-Known Member
I guess it depends on the particular situation. For most sealed rooms ive built and came across...hooking the dehuey and mini split up to a controller with relays was a no go. For bigger rooms or areas this could be different. For bigger rooms big hvac units could fare differently.
 
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