In my attempt to control my duckweed, it doesn't play nice, I decided to leave my filter turned off this morning after putting it on the shade side of the tank... I wanted my bright plants to get more light today. This way I KNOW it won't switch sides.
I tested the ammonia levels at lunch and they are no different than the last few days, just over the zero. I am going to leave it off for the rest of the day to see what happens with the levels this evening.
With people going on about the filter media and bacterial nitrification being the most important, this just indicates to me that it may not be as large a factor as it is often considered, which I suspect anyway. The substrate and plants I would expect to more than compensate for the filter's contribution.
I wouldn't want to leave the filter off too long, who knows what creepies might be growing in there in the dark.