Ziggy953
Aquarium Advice Addict
That would be mineral deposits. Chances are you have hard water. I have a FW tank that has been set up for a little over 5 years now and I don't see that on the tank and I have bubble curton in the back of the tank.
I do know that the water and vinegar solution will remove it.
I do know that the water and vinegar solution will remove it.