For the last few months I've only been doing fortnightly 20% water changes and I have a sparkling tank at all times, strong healthy plant growth, very little algae and happy fish. The nutrient regime is potassium and iron on alternate days and micros twice a week. No nitrate or phosphate except what gets added via fish food. In the past when I've not dosed NPK, the tank inevitably crashes, so this success is a revelation to me. The benefit of this method is the time saving re the water changes and making the RO plus excellent algae control. The tank is 100 litres, ember tetras x14, cardinals x10. The change water is RO remineralised with Dennerle GH/KH to TDS 100. There's a CO2 reactor at 1 bubble/second. You need a fair amount of surface agitation. The tank water is TDS 200. The nutrients used are from Seachem Flourish range: Iron Potassium Comprehensive Supplement Micros (keep in the fridge when opened) This is what I dose: Sunday - Iron 2ml, Micros 2ml Monday - Potassium 4ml Tuesday - Iron 2ml Wednesday - Potassium 4ml, Micros 2ml Thursday - Iron 2ml Friday - Potassium 4ml Saturday - Iron 2ml Sunday - Potassium 4ml, Micros 2ml Monday - Iron 2ml Tuesday - Potassium 4ml, Wednesday - Iron 2ml, Micros 2ml Thursday - Potassium 4ml Friday - Iron 2ml Saturday - Potassium 4ml This regime is from Youtube, Mass Aquariums: "How to take care of a planted tank: lights, dosing fertilizers, pressurized cCO2, water changes". Plants from the tank: The CO2 reactor can be seen in the middle chamber below: Hope this is useful.