Stem plants, nutrients, and browning java fern

• pH:
• Temp:
• KH:
• GH:
• NH4:
• NO2:
• NO3:
• PO4:
• Iron:
• Dosing: 5 mL Flourish, 0.5 ppm iron chelate, 5 ppm Flourish potassium (25 mL)
• NO3:PO4 Cumulative Dosing Ratio:

Notes:
It's only been a little over a day since I've added the new plants, and I've already noticed that the algae levels, which had initially come back after the green water algae was filtered out, are noticeably lower. The water is also still crystal clear. The plants are also slowly recovering in terms of growth. What's more, I've noticed that in the same time period of a day or two, the java fern leaves have suddenly started to turn brown again. It seems that with the increased plant growth and all the new plants (about 5 bunches worth of new stem plants), the excess nutrients are being taken up by the stem plants, leaving less for the algae and java fern. It seems that the java fern is a poor competitor for nutrients, which may be made worse in high lighting conditions.

I'm still stumped, though, as to which nutrient deficiency is causing the browning. After researching online, it seems that this is a common problem that many people have with their java ferns, but no one seems to have a grasp on what is the cause. I've read that some people think that low nitrate levels might be the culprit, but I've been consistently maintaining NO3 levels greater than 10 ppm (usually around 15 ppm). I've also been keeping the phosphate levels up, so I don't think that is the problem. Potassium may be a problem, but I was still having the problem when there were levels of 33-66 ppm of potassium. In fact, I noticed the problem originally starting a couple months ago when I increased dosing of Equilibrium (which is my main source of potassium). It might have just been coincidence, though. It might be some micro nutrient deficiency. Now that the plants are recovering, I want to try to ramp up on Flourish and iron chelate dosing to see if that makes any difference with the ferns.