Dry spots on sugar leaves, plant late in flowering, also spotted on another one in the same reservoir

Looks like phosphorus deficiency. You are also feeding too much nitrogen. In flowering a npk ratio of 1-2-3 is best till you get the hang of nutrition amounts. Change the water with a high diet in potassium and phosphorus and minimum nitrogen since you ate pretty rich on it. Ph about 6.2 to 6.3 range is better as well. Good luck and should stop those signs once done. 🌱