I sounds like nutrient deficiencies. You said it came unrooted so what I would do is take it out of the substrate, trim off the decaying parts, then float it until some roots develop before planting it again.
The API Leaf Zone has potassium and iron which is good but you also need to pick up something like Seachem Flourish Comprehensive which has a larger variety of nutrients in it. Be sure to use them as directed.
The API Leaf Zone has potassium and iron which is good but you also need to pick up something like Seachem Flourish Comprehensive which has a larger variety of nutrients in it. Be sure to use them as directed.