I am fairly new to co2, after seeking advice on algae the following was suggested to me. Everything I have always read or told this will gas off your co2. The line of conversation said that my algae was caused by my co2 shutting off at night(fluctuations). Also I started using the airstone at night because of minimal surface agitation.
i run both (co2 and airstone) ,all day and night,, but my airstone is behind a tall rock and only disrupts the surface in a small space bettween branches with plants growing off them out of the water. Surface agitation is minimal in the rest of the tank(65 gallon), but the flow is strong and elaborate enough that with the co2 going through an inline diffuser i can see the mist travelling around everywhere before it leaves it reaches the surface(drop checker always same light green). I do have to refill my co2 more often but i got 2 5lbs bottles so i dont ever run out. After years of diy co2 fluctuations(yeast mix) causing bba relentlessly, i decided to not turn off my co2 at night to avoid fluctuations. Takes more co2 (cant count bubbles per second) but higher o2 levels accomodate higher co2 levels in less harmful ways to your fish. as both gases can exist in the same place without forcing the other out. Dennis wong on youtube has some detailed videos about optimizing co2 levels. Theres always ways to incorporate surface agitation into hightech tanks for sure
need lots of flow and o2 to keep gsa away. People who havent had it are always against air stones and surface agitation in general.Just as many people are always turning their co2 off at night,, due to not having experienced extreme bba as a result of fluctuating co2 levels.Higher o2 levels accomadate higher co2 levels as both gases can exist independtly of each other without one forcing the other out of the tank.So airstones cant and wont cause fluctuating co2 if you have it dialed in properly and enough flow to make sure co2 circulates through the whole tank before the airstone can draw it out through surface agitation.Turning it on and off would for sure lead to gsa after first missed water change for sure. Surface agitation and logical flow paths have become just as much a part of the balancing act as nutrients ,co2 and lighting for me.Diffusion of co2 externally is key for any of this to work though. Algae always changes everything