When I was a teenager I would ferment apple juice in a one gallon jug and pipe the co2 into the impeller of my filter. It worked really dang well for a shitty pruno reactor and cost next to nothing. (You can use sugar water and yeast, too. I just obviously had such a refined palate back then)
If you want to get really bare bones but don't trust your plumbing and tubing skills you could get something like this
Yosoo DIY Aquarium Planted Tank CO2 System kit pro Tube Valve Guage Bottle D201 https://www.amazon.com/dp/B00UYMO6SQ/ref=cm_sw_r_apan_i_5M3WFJVK3Z9P4YT28ACJ
Plenty of videos online for growers who use the same concept. Good for small tents, can’t confirm or deny the effectiveness of them but they definitely make co2.
Just google diy co2 generator.
Going to leave it for a week or so and then upgrade the bottle sizes and add an additional clean water bottle so I can easily see how many bubbles are going through
This is the same setup, cheaper though, that I use. Had great success with it too.
Do you have links for exactly all of the connections? I'm getting really tired of all this algae and really want to start a carpet, so C02 here I come.
EDIT: Once again, google has proven very useful lol
I have no idea how this stuff works but it's pretty cool!