Unknown plant

This is likely a potassium deficiency, probably caused by incorrect ph, but may be caused by just simply lack of potassium in the soil and lack of nutrient additives. Start measuring water ph to 6 up to 6.5 or if its already measured in those ranges, add a bloom nutrient to your feedings. Hope it helps, if you don't mind selecting answer, it helps a lot in grower of the month contest. Thanks and good luck growmie