How to Improve Hydroponic Leafy Vegetable Plant Productivity by Balancing Nutrient Solution, Total Dissolved Solids (TDS), and pH Completed with Literature Review on Standard Vegetable pH & TDS Requirement to Support Sustainable Development Goals (SDGs). ASEAN J. Sci. Eng. 2025;6(1):113-128. doi:10.17509/ajse.v6i1.89992