It looks water stained somehow. Tried vinegar tried bleach tried CLR and nothing has helped. Any idea what this could be? I don't think it's calcium.... I know that there used to be a background taped to the back and the back is now accidentally the front- unsure what to do
Sent from my SPH-L900 using Aquarium Advice mobile app
Sent from my SPH-L900 using Aquarium Advice mobile app