I don't believe this is an emerged issue with the plants.
You are using API root tabs. these provide nitrogen, potassium, and phosphorous, and iron. that is 4 out of the 14 nutrients that are essential to get plants to grow. Nitrogen, potassium and phosphorous are 3 of the 6 macro nutrients. you are missing the other 3, calcium, magnesium and sulfur. Iron is a micro nutrient.There are 7 other micros needed.
excel only provides a source of carbon and has no macro and micro nutrients.
If you are short on just one nutrient you may get little to no growth and your plants may start to die. Now your water and substrate in your aquarium may have some of the missing nutrients but it is unlikely they will entirely cover the shortage. Your plant have likely greatly depleted the missing nutrients and are now suffering. Short term you can do a a large water change to boost nutrient levels. Long term you need to get a more complete fertilizer. I would suggest Niloct.com Thrive. It is much more complete than any API or Seachem fertilizer.
The fulll macro list in Nitrogen (N), Potassium (K), Calcium (Ca), Magnesium (Mg), Phosphorous (P), and Sulfur (S)
The full micro list is Iron (Fe), Chlorine (Cl), Manganese (Mn), Boron (B), Zinc (Zn), Copper Cu), Molybdenum (Mo), and Nickel (Ni)
Last edited by Surf; 04-10-2019 at 10:16 PM.
Reason: Removed unintended bump