It is completely “sealed”
But the lights are ducted in from outside then through the lights and out the exhaust. However with all of the duct fans running during the daytime hours I know I have some leakage if not a lot from the fixtures fans and ducting itself.
Hi Nick,
Have you adapted your average light output and temperature:
1,000 µmol/s/m² would be needed in order to get the full potential out of your plants. To reach that goal your would need at least one (dimmable) 1,000W HPS per 15 sqf or 630W of dimmable CMH per 10 sqf (depending on the dimensions and conditions of your room)
An increased temperatur is also important.
Watering and fertilization strategy has also be adapted
cheers
Christoph
A good place to call is Praxair. I will be using their service in a “micro-bulk” platform.
A semiperminate tank will be installed in an outdoor room (to avoid leaking issues and liabilities in the working area) and then topped up once or twice per month and then I will he charge by the weight of consumption.
They’re very experienced in this and can be very informative about this subject. One call to them and the math I had done already was confirmed and a programme was developed.
Highly recommended them as a company.
I would monitor the conditions in the room with and without CO2 supplementation and then compare those figures against growth rates. With my research I’ve found no appreciable growth rate difference (at least not enough of a difference to justify the expense), when increasing CO2 saturation above 950 PPM when my room conditions are 76-80°F and RH sits around 55%. That’s not to say that I could be wrong, it’s just what I’ve observed in the facilities I run.
I love the models provided by @cschubert above, they’re very demonstrative!
If you’d like to speak about your CO2 strategy, I can be available to you. We’ll schedule a time to set up a call. 
Another thought for you moving forward, if you plan on doing extraction near by and use CO2, you can vent from the extraction machine to your grow.
It is far more efficient than trying to use the CO2 recycling systems out there.
Great point @Soma! I’ve often off gassed from my brewery during fermentation into the cultivation space to increase CO2 levels!
Don,
Before you invest too much into gassing CO2, most of which escapes into the atmosphere, please check out co2gro.ca I have been working with them for the past 6 months and we have numerous trials going on Canada and the US in Cannabis as well as a number of other crops.
CO2 GRO has a patented system that infuses water with up to 2000 ppm of co2. The infused water is applied to the crop via mist system or sprayer, beginning with clones and up thru the grow phase of production. We are continuing with larger trials but I can say so far, results have been very positive.
I would be happy to discuss this with you further at your convenience,
Sincerely,
David Marshall
MorningStar grower Services
Hi Nick,
our research has shown that the yield of cannabis can be increased up to 20-30 Percent by using CO2, depending on the strain and also the initial situation. Given that
It is quite clear that, if the plant can use that massively increased input, that something must happen with those ingrediances 
The hard part is to figure out/optimize the conditions in order to allow the plants to use CO2, fertilizer, etc. properly.
So in the end the initial investment in ‘CO2’ is not the problem since you will get back every Dollar invested. The hard part is to get controll of that process 
So if you are still interested we could figure out a strategy that will work for you! It is worth it but it will be some ‘hard’ work too!
cheers
Christoph
David,
Do you have any case studies you can send me?
Hi Bryan,
that document gives some ideas about the potential and technology:
It is directly from the website of co2gro and the only document I have found so far!
cheers Christoph
Hi David,
To me the approach seems to be quite reasonable too. I would be also interested in getting more informations since I could provide access to some European growers who might be interested in testing that technology too.
But one question: Whats about the blooming phase, since I am a bit concernded about mold!
cheers
Christoph
This is a great question. Granted most people do spraying anyways, but the frequency of dosing would be of concern.
Absolutely it’s a technology to be looked into and my interest is there.
Thank you! Very useful information here on CO2 application on cannabis.
I’m wary about spraying anything, ever, for any reason. I would never recommend spraying after the flowers have begun to set their shape (around weeks three or four). I need to know more as molds, rot and PM are major concerns, especially with high RH values. Have any studies been done or white papers published about the mold mildew issues?
Growernick,
I absolutely agree, spraying during the flowering phase of production would never be done for Co2 applications and shouldn’t be done at all unless something really extreme is going on with the crop.
Co2 infused water is applied as a mist or lite spray during the propagation and grow phases. This is where it will have the most impact on growth.
David
That makes sense. If you are going to apply anything as a foliar, it always should be done during the vegetative phase. Thanks for the explanation 
So despite some interest in infused water I would prefer to use liquid/gas CO2. I have talked with a bulk vendor who can install and refill a 750 pound tank in the next few weeks.
My Question now is that the regulators I’ve seen are almost all 0.5 - 15 SCFH and it will take about 18 CF to get to 1000 ppm in an 18,000 CF room.
Thus the Sunlight Supply CO2 calculator suggest “Flow exceeds capacity of valve”
While this calculator allows me to set the flow rate
https://www.hydroponics.net/learn/co2_calculator.php
Result
Grow room area: 18000 cubic feet
Amount of CO2 required: 18 cubic feet
On time: 72 minutes
I’m thinking I need a regulator with a higher flow rate? does anyone have a suggestion for a high flow rate regulator? with solenoid of course
Hey, @Don!
Cool to hear you’ve linked up with a vendor!
I highly recommend investing in a CO2 controller unit that has a built in PPM monitor that will turn on the regulator according to your programmed setpoints. I love controller modules produced by Titan, Sentinal, and Link4. Some of these controllers are part of a more advanced integrated environmental control system and turning on/off the regulator for the CO2 is just a function of the unit. I have used Link4 614’s and 624’s for many years now and I absolutely love them. @Link4Controls is here on GNET and you can reach out directly to @Link4Dean here, if you’re curious about what they can do for your cultivation space. I love the “set it and forget it” nature of the product.
In my experience, I’ve always been amazed at how quickly the gas expelled from a tank can raise the PPM in even a large space rather quickly. I suggest you test this out or yourself before you invest in a high flow regulator.
You can purchase a normal regulator from Growers House for $79 and be on your way!
Thanks Nick I already have a the meter and controller, I have my OG Sentinel CHHC-4, as you mentioned it monitors and controls A/C, Heat, RH, and CO2.
I guess I shall just take your advice and just start testing with the CO2 regulators I already have 0.5 - 15/SCFH.
Don,
I think moving forward with the CO2 gas is a good idea. You would be a great guy to set up a side by side trial with. You could use gas in one room and infused water/mist in an other.
We’ve got engineers designing the systems for easy installation etc. and will keep everyone updated as we move forward.
Stay Tuned…
David
