Depending on your living space and how may people/animals you have living there, I don’t really think that ancillary CO2 is going to benefit the Grobo much as the light just isn’t strong enough to really utilize it. I could be wrong.
I have used these in the Grobo
https://www.amazon.com/Green-Generator-Contains-pads-Hangers/dp/B01GFI97ZY
and saw no mareketable difference, but I did see a difference in my other set up with much more intense lighting.
I make a Sugar Yeast brew at home, its pretty low maintenance and depending on the size of the reservoir, it adds about 200-500 passive co2 ppm for my plant in the grobo. Since my grobo is in a sealed grow room and also is my work office, the passive CO2 in my room is much higher than normal.
You can also add a small mushroom grow if you are concerned with the lifetime of the CO2 gas. Added CO2 gas wont add much benefit during veg so if you want to budget on resource, save the CO2 flowering stages. The added CO2 will also help growers who have issues with high temps or limited to spaces without adequate airflow.
The green pads shared by @Centervillain works well too, however they need to be replaced regularly as well, they last longer inside propagation domes. I would recommend CO2 for grobo users.
I for one am glad that the grobo team recognize the CO2 challenges the grobo may have and doing something about it like adding some kind of CO2 solution to the store. I personally feel CO2 plays a huge factor with yield and growth and is what allowed me to add so much light to my previous grow to max out yield without killing her.
I was thinking of using a sugar yeast setup with a single 2 liter bottle w/ a hose coming out the top and cascading down over the top of the plant? Any thoughts because every diy setup I’ve seen uses 2 bottles and not quite sure why u need 2 bottles
@Highhopes that works well. I use a similar set up however with a much wider container. The bigger the container is, the more CO2 you can generate with more cultures and sugar. I also add tomato paste to the mixture to give the cultures an extra kick to generate CO2. I seen some people making these with 17 gallon bins and adding airstones to it to emit CO2 and generating 1400 ppm of CO2.
2 Bottles is not necessary unless you are looking to build a dual pressurized chamber CO2 generator like with Baking Soda and Citrus Acid which works as well however super high maintenance. I did it for 2 weeks and it gave me tendonitis, not to mention I went though like $40 worth of citrus acid in 2 weeks to keep ppm consistently at 1200-1400.
Awesome thanks, just wanted to keep it simple and not add a bunch of bottles and tubing in the grobo if I didn’t need too, and if it doesn’t add to the grow I’m only out 5 bucks!
@Highhopes here are some post around CO2 that I posted with my previous and current grow if you are looking for examples of what I tried, I didnt post about the dual pressure chamber setup however:
Good deal! Thanks again
I just got mine and a couple questions.
it says to fill with a liter of warm water. Where on the bottle do I fill to?
is there a certain stage that bit should be used since it would be expensive to replace every 2 weeks?
should it be in the Grobo or behind near the intake fans if we have 2 Grobos?
= Just add 1 liter of water. The directions tell you the amount of water to add, no need to worry about where the fill line is on the bottle.
= Flower
= Bottle should be inside the Grobo. Resting on the reservoir lid.
I’m American. We don’t do liter 
I would need to go buy a measuring cup or something. Or maybe a 2 liter bottle of something and fill it half up.
Just convert the units? Google?
I don’t see anything like that in the Grobo store.
@jamestournas
You can either click on the link I provided for the CO2 Generator in the first post or go to the website, Shop Now, Grow Supplies.
Found it - thanks.
It lasts two weeks - When do you use it? Flower stage?
I’m american and I use metric. It’s very popular and easy to use as long as you can count to 10. Also 1 gal = 3.875 liter.
I bought one for my grobo, came in today. Didn’t realize how big the bottle is, almost as tall as my squatty little plant. I kinda don’t want it in there as it takes up a lot of space and my plant pretty much fills up the space entirely from wall to wall on all sides. Definitely has it cramped in there now… kind of wanted to see how it would do behind my grobo just under the intake fans but I also feel like that won’t be as effective as being closed in
Yes you can make this at home it’s a very simple design… the bottle is the thing that you are buying, so be careful. It’s just a diffuser
Could I potentially use a small bottle and use the refill pack and cap to essentially do the same thing on a smaller scale?
