The water level in my nano aquarium keeps fluctuating but the ATO seems to be working normally, what is happening?




It is very common to see water level fluctuations in the back sump/filter area on a nano aquariums. Sometimes this will be more pronounced if the main pump is in need of maintenance or the filter media is beginning to block. It is also possible that a surge or wave pump can push water towards the overflow comb into the filtration causing a fluctuation. As a result of this it is common to see the ATO sensor submerged deeper than the main sensor point and will not be a problem.