Grit in black tank

[Lyle & Cath]

I replaced the pressure sensor in my black tank in the Apex and found that the sensor was packed full of rough grit like course concrete. I explored on the inside of the tank (what fun) only to find that the interior walls seemed to have a coating of this stuff. I know its not coming from me, and I know its not the bio stuff we use in the black tank. Does anybody have any ideas what it might be and anyway to deal with it. I flushed the tank for about an hour prior to pulling the sensor and actually had clear return. Any help would be MOST appreciated.
Thanks,
Lyle
Lyle & Cath
Apex 1

[Lyle & Cath]

I replaced the pressure sensor in my black tank in the Apex and found that the sensor was packed full of rough grit like course concrete. I explored on the inside of the tank (what fun) only to find that the interior walls seemed to have a coating of this stuff. I know its not coming from me, and I know its not the bio stuff we use in the black tank. Does anybody have any ideas what it might be and anyway to deal with it. I flushed the tank for about an hour prior to pulling the sensor and actually had clear return. Any help would be MOST appreciated.
Thanks,
Lyle
Lyle & Cath
Apex 1