CO2 7mm hose into top of grobo

Hi guys!
I‘m thinking about building a co2 supplement which uses canisters for sodas. Hence I want to guide a hose into the grobo, preferably 7mm diameter and to the top of grobo so the gas can pour down. Any ideas/hints please?

At grobo support: when the plant has increased growth due to the co2, would grobo add addtional nutritions from other bottles to keep up?


The nutrition will not be affected by the CO2. Nutrients only dispense as told by the recipe on the completion of the drain and fill. They usually dose pretty high as it’s supposed to last a week and account for top offs of the reservoir from what I’ve gathered

@Vicc used CO2 but also added nutrients to his top offs and measured pH and EC to make sure it was correct

Apparently @Jamminbear was running a cord through the carbon filter spot up through the door for an LED light so maybe you can do something similar ? I don’t know personally How that went down but he says there’s an inch gap when you close the door which pressed the cord in a bit and he was snaking his cord through the carbon filter spot and out of the top of the Grobo.


Cool thx for the info!

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Here are some information I shared a few months back regarding my CO2 setup.
This is now being used in my tent, inside the grobo, I use a yeast brew.


Awesome work! Thx for the info!
@Vicc what do you use for the yeast brew?

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In a container, fill it up half way with warm water and add the following:
1 TSP Active Yeast
2 cups of sugar
half cup of ketchup

once a week, I dump out half of the liquid and fill it back up with warm water and 2 cups of sugar. This adds about average 250-300 consistent (passive) ppm for me. Block light from hitting container, I use black out film and warp my container. Keep temps around 80f for the yeast brew. I add more ketchup or a puree tomato when the liquid returns back to a clear color.


Added Co2 to the mix is very hard to pull off efficiently I’m not trying to be negative on the topic just I know what I was dealing with (by far the hardest add on is Co2). If you plan to give it a try you need these factors mastered first or your wasting your time and money (my Thoughts)

  1. Daytime temp needs to be 85 to 90
  2. At those temps your going to need to keep your RH% around 60% even in flower to achieve your correct VPD…
  3. Have to maintain Co2 PPM at 1200 to 1500 (day)
  4. How are you going to stop Grobo from exhausting all your Co2 out of the box?
  5. Need alot more lighting power than Grobo has.

You need to find a way to solve problems 1 to 5 before I would start the project… The only way I see Steps 1 to 4 being possible is to have this environment in a tent and your Grobo inside the tent… Step 5 don’t see that happening in Grobo…

I recommend you spend your time and Money on ways to always have your VPD in line first (this will give you bigger yields over Co2)… This is so much more important than Co2 that’s what I did!!

I hope this helps if you have any questions on the topic let me know I believe there is only a handful of users here that have experimented with Co2


@Mpower11 is correct, CO2 is very difficult to manage and hit optimal ranges, and will only add about 20-30% yield of all the conditions are correct and of course genetics. However I have to say that adding CO2 to a grobo isn’t ideal however can definitely help in situations where the grobo is placed in a area in the home where there are not sufficient airflow and CO2.

Using a CO2 tank in a grobo without a sealed tent is wasting money. Passive CO2 as an additive would be the way to go with the grobo.

I’m lazy I just use liquid Co2 with Regulator… But I’m thinking about getting a Co2 burner in the future


Here is a VPD chart to help you…


For my tent I use a CO2 tank that I can refill every 3 months for $25. For my grobo, just a sugar yeast brew, its much less maintenance than doing a reaction chamber with citrus acid and baking soda lol. Burners are nice if you live in cold areas, unfortunately I’m in Cali, so I resort to CO2 Tanks, Yeast Brew and Mushrooms to increase my CO2 ppm. The mushrooms alone give me a 600-800 passive CO2 alone so my tank, and regulator don’t have to expend so much resource.

I also have my CO2 regulator and controller shut off at high temps and turn back on at low temps to save on expended CO2 during cooldown since I am not using a recirculated AC.

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I so want to get that CO2 sensor for the Hydro X next!!! I got my autopilot as a gift before getting the hydro X so I’m stuck using it at the moment but it would be proper to have everything onto the Trolmaster app!

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Love it!!! What is stopping me from getting a burner is it is going to increase my RH alot… Then I going to have to run my dehumidifier like crazy to keep it down… Then the crazy amount of heat produced by the dehumidifier is going to make my exhaust fan turn on all the time… In turn will not be able to hold my Co2 PPM… This is what I mean about Co2 being the biggest pain in the ass you fix one problem then you make an other… To solve this problem I need to add Ac to the mix and I’m not sure I want to do that at this time

Don’t forget about the Aqua X :+1::+1:


Done! Got it during Black Friday sale! :partying_face:
I still need to order the PH and EC probes but I am currently using the Milwaukee Instruments I previously got on craigsllist. Slowly but surely =]


Double love it!!! You been spending some $$$ I see… hahah

Here is some tips I can share…

If you end up getting the PH and Ec Sensors I would get the inline ones PPH-2 and PCT-2 (The quality of the probe is alot better… (You don’t have to install inline)

Back on Co2 if you want Co2 to stop injecting when Exhaust turns on you need to get DCC-1 (Dual Condition Adaptor)

Also if your connecting your lights to TrolMaster you will need a lighting adapter ( LMA-XX) the xx could be 12/13/14 etc… Does your light support “dim to off”

I don’t want to hijack this topic I think I better stop here but I have more information if needed… Besides Chris I don’t think anyone else here is using Trolmaster I can save you alot of headaches and time…Missing needed modules set me back weeks from starting my last grow…

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@Vicc Cool idea :grin: which yeast do you use? I‘m lucky, i brew my own beer, hence I have a variety of.


@Mpower11 ok I see, there are lots of other points :thinking:
My RH is constantly at 40% during early vegetation. I guess it will increase with a bigger mary.
Cool, thanks for the input!

any bread dry active yeast works, you don’t need much since they colonize after starting up.

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@Parcival you want it around 65% RH, your plant will appreciate it.

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