Anyone else with multiple tanks where one just grows way better than another?

I have a bunch of tanks running, mainly with the same equipment and water parameters, and similar substrates, but my daughter's low tech 10g dirted tank is just so perfectly balanced. I can't seem to match it in my other tanks. Her tank just cruises along, growing steady, crystal clear water, and only very light water changes about once every two weeks. My 46g bowfront looks nice, but it's way higher maintenance then the 10g. Anyone else have this happen to them? It's a mystery to me why this occurs.