I need some help with this. Today I went in to suction out some old food and waste from the gravel and noticed that everything had black spots on them. It looks like someone sprinkled black charcoal on everything. I took all of the ornaments out of the tank, rinsed them off. Took half of the water out and cleaned off the sides of the tank. I also noticed that the charcoal filter was in desperate need of being changed. I think I missed the last change. Could that have caused these black spots?
Even though I cleaned all of the ornaments in the tank, changed the filter, and added new water, I still see that black on the gravel itself. Should I empty the entire tank and replace the gravel?
The tank is 10 gallons. I have a heater in it and a filter. I run the light from 8 a.m. until 8 p.m. I've been reading that others change a certain percentage of water each week. I did not realize that I needed to do that.
Please advise. I think I'm taking care of this aquarium all wrong.