I started growing three tomato plants in my windowfarm using maxsea 16-16-16 plant food and started to notice that a portion of the stem is purple and the underside of the first two leaves are purple. The new leaves on the top are perfectly green. I read that this is evidence of a phosphorous deficiency. I was a little conservative with the amount of plant food I was adding in the beginning but I’ve recently been using a 1 teaspoon/gallon of maxsea 16-16-16 in a purified water solution. Is it wise to add a phosphorous supplement solution to my reservoir?! I also have my pump watering non-stop.