funguas

My setut up is a planted Fuval flex 15 gallon tank with 10 Cardinal tetras, 10 Amano shrimp, 12 cherry shrimp and a Betta.. Water parameters are 5Gh, 5kh, Ph@ 7.0, Ammonia @ 0, Nitrites @ 0, Nitrates @ 10-15 ppm, TDS 380 ish....I have a growth in the Aquarium, that I cannot identify nor find...