If changing water introduces CO2 which we want the plants to adapt away from in a low light/tech, no CO2 set up, how do you deal with evaporation and dropping water levels. In my little tank (35l) I've a luminaire and a combination of the heat from the light and an open top to the tank means that my water levels drop reasonably fast.
How do I reduce the impact of topping up on the CO2 levels?