I would be more inclined to believe your tank is all balanced if you provided some actual numbers and proof. How often do you measure TDS? gh/kh/ph? micro nutrient / mineral levels? oxygen levels?
Its one thing to simply know your nitrates are not through the roof, but its not right to assume the tank is all healthy without constantly check the parameters of the water to ensure stability and appropriate levels for livestock to live and thrive in.
Anyways I don't want to side track the thread but my point is to just consider everything and not just focus on nitrates and a rules for water changes.
Loads of fast growing plants will be a great addition. consider terrestrial plants as well (pathos). also dropping the temps to the lower range of the fish can reduce metabolism and would be something you might want to look into. this would be done gradually and also ensuring not to drop it too much to harm the livestock.
Small vacuuming to remove waste would be a good idea as well. also a good lid to prevent evaporation, the lower temps will help with this too.