Leather Crown Not Healing Completely

[ruxsir]

I got this leather as a frag around a year ago. It was a quarter of the size without a trunk. As it has grown, there has been one spot on the crown that has not completely healed and approximate nicely. Any guesses as to why?

 

[mcarroll]

Tank too clean? You're making us guess.....

Please post some basic info about the tank and it's history as well as all you water test results including s.g. and temperature.