I took the bubbler out of my low tech planted set up because I read that it will dissipate the CO2
that builds up to some extent when the lights are off, which the plants then use up when the lights come back on (this is the idea behind the Walstad "siesta" in the middle of the day, which will allow for some CO2
to build up as the lights are off, which can help feed the plants through the rest of the day). I don't have any way to know if the bubbler was actually off-gassing the CO2
though. Spray bar could help with surface agitation.