Good evening UKAPS
in my opinion "what it all looks like" is the personal option.
What is happening is what it's all about.
CO2 dissolved in the water + appropriate lights (separate topic) to maximise plant growth is the business.
Remember the CO2 in the canister is relatively cold being under pressure. It gets released not yet dissolved into water that is between 24 & 27 degs C (read much warmer) and it doesn't defy physics it conforms - expands, become "lighter" and heads for the surface.......... who knew??
My Scottish genes immediately say "waste not want not" so I'm on auto pilot to find a way to maximise the CO2 and facilitate optimal photosynthesis.
So I'm wanting CO2 to dissolve in water returning to the aquarium - NB not to the canister (closed system) filter, because I respect the bio column that keeps my "animals" happy to be alive. (no ammonia NH3/NH4 and no Nitrite NO2).
How you do that is entirely up to you and your understanding of the physics of dissolving CO2 into water. The requirements for such a feat are:
1. Slow the water flow down (in my experience, to between 1/3 or 1/4 of canister pump capacity), achieved by for example increasing the diameter of the return pipe from say 25 mm to 75mm or 100mm (depending on how strong your canister's pump is),
2. Injecting the CO2 into the stream at this point in as small a size bubble as I can (small bubbles dissolve faster than big bubbles - (no PHD in physics required) then once I can observe the return water has ZERO bubbles (CO2 has done 2 things, warmed up to parity and then the decent thing, dissolved) the water, now loaded with the CO2, moves from the larger diameter tube to
3. The "normal" 25mm tube, accelerating back to normal flow rate and re-enters the aquarium......
No more CO2 snow storm, no additional hardware in the aquarium, no CO2 waste (God forbid) and vigorously growing plants. AND as an added bonus the drop checker responds quicker too, going from sapphire blue to emerald green in a few hours........ so I ask .... is there a down side? Answer.... No all good this side.
That's how we do it in Cape Town, South Africa (southern suburbs only at this time)
I hope this helps maybe just a little.
Cheers PL