My ludwigia plants have been growing great until the last week and something has gone wrong. I looked on Chuck's website for NUTRIENT DEFICIENCIES and it is pointing to low potassium but I have no way to see what the potassium level is in my tank. I have been adding potassium nitrate because my nitrate was at zero and I just tested it and it is at 10ppm which is high for my tank (15 gal). I do water changes every week and have a DIY CO2. I tested my PH and it is at 7.8 and the KH is at 251 ppm which per Chuck's calcs make the CO2 at 7ppm which is low. The phosphates tested somewhere between 5-10 ppm which is way high. I have added pics below and would apprieciate anyone's input. Also to let you know that I am running 3-15watt bulbs for lighting for 12 hrs per day.