I recently fired up two of our pods/tanks. When filling them with water I used an RV water filter when filling the tanks. We've had them operating for about 6 weeks and we have little rust spots on the bottom of the floor(fibreglass bottom). I've tried to rub them away but that hasn't worked too well. All of my alkalinity and pH levels are in the normal ranges.
Does anyone know what this would come from? And if so, is there a solution to get rid of the spots?
Thanks in advance for any assistance.