Hydroponic systems are known for their simplicity and low maintenance requirements, but it is important to understand how to maintain water quality for optimal plant growth. You can follow a 'fill-up-and-adjust' strategy. Top up: You can top up the water with the nutrient mixture. This helps conserve water and nutrients. Nutrient Adjustment: When filling the reservoir, you should also monitor and adjust the nutrient solution. Over time, as plants absorb nutrients, the nutrient concentration can change. Cleaning and maintenance: Even if you do not change the water completely, it is important to keep the reservoir clean. Inspect the roots for signs of rot or algae growth. Clean the reservoir and water pump regularly to prevent clogging and ensure adequate oxygenation. Changing the water: In some cases, if the nutrient solution becomes unbalanced or if you encounter persistent water quality problems, you may consider changing the water.