I have a 29-gallon planted tank with mollies, mystery snails, and several live plants.
I use Seachem's Potassium, Nitrogen, Phosphate, and Flourish liquid fertilizers in the specified doses twice a week or so. I also use Seachem Flourish root tabs, and recently added more of those. However, it doesn't appear to be helping. I don't use any kind of carbon dioxide supplementation.
I use white LED lights. The aquarium gets indirect sunlight. Right now nitrates are higher than usual at around 25 mg/L (I'm working on reducing that, they're usually quite low; in the past they've sometimes been pretty close to zero) with zero nitrites or ammonia. Total Hardness is on the high end, somewhere between 75 - 150 mg/L.
Does anyone have any suggestions of what the problem may be, or of other things I could try to help the situation?