For cleanup crew, I have a Farlowella, 2 Zebra Nerites, and 3 Rabbit snails in a 37 gallon. I'll look into getting some ottos and/or some more nerites.
My black gravel (approx 7 years old) is breaking down and flaking it's paint. After reading about silicates and diatoms, and not finding any clear photos to confirm, I assumed it was diatoms.
Thank you for your input!