For my 5 gallon tank, I have a Top Fin submersible heater made for 1-5 gallons. It's the flat kind, not the cylinder, and keeps the temperature at 80 degrees or higher.
The tank has been running for over a month now, and everything is fine. However, there's some white "stuff" growing on the heater. I've tried to research what it could be, but I haven't found anything similarly close. The white stuff stays on the heater and it hasn't spread or shown up on anything else (decor or filter). You can also see on the suction cup some brown "stuff" growing around the edges.
Does anyone know what this could be?? I've tried to scrub it off but stopped myself in case it may be beneficial bacteria. Thanks everyone! Any input would help tons!