I tried the bell system for a short while (the ISTA brand version) in a plant holding tank... not sure if it really worked because my drop checker stayed blue throughout its usage and plant growth wasn't noticeably different, but i guess there was probably at least some Co2 concentration in the water, but just at low quantities. It requires regular daily top-ups to run though, not automated like a solenoid regulator system.
The dissolve rate on such systems really depends very much on the relationship of the surface area of the Co2 in the bell chamber versus the tank volume (each bell chamber has a fixed surface area though)... the more surface area the better the diffusion rate, so for larger tanks, you'll need to install larger bells or more bells to increase the dissolve rate. You can see the kit instructions recommending to install multiple bell chambers for larger tanks.
Here is the setup and usage video for the ISTA set, they also demonstrate using additional bell chambers to increase the Co2 diffusion rate:
I guess if the whole tank is full of multiple bell chambers then can see better effect.
Anyways... if you want to maintain consistently good growth for all your plants, then its best to just go for a proper Co2 system from the start and stick with it. If you use Co2 injection for a while to grow out the plants, then remove the Co2 supply, those plants that utilized the Co2 to grow well will run into carbon limitations again and might just end up deteriorating over time, it'll be back to square one.
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