Black tank capacity

[scootsk]

Good morning all,

I’ve been having an issue with my black tank. The toilet spits back when the tank is just over half full. Today I tested the capacity of when the toilet starts to spit. I put a water meter on the rinsed and the toilet started spitting at thirty gallons. My capacity is supposed to be 50 gallons, leading me to believe the vent pipe is not installed properly and is under the water level at 30 gallons. Any one else have this issue, have you fixed it?
2019 3791RD

 

[Bobby P2]

Possible vent problem but I Wonder if you have buildup in the tank. Poop Pyramid will likely cause that to happen.

 

[scootsk]

Definitely no poop pyramid. At least not to my knowledge. I have never left my black tank valve open. I only dump when 2/3 full and most times follow with another dump of a 2/3 tank of fresh water. Not to say my poop might be concrete like and fall to the bottom and set lol. But I understand what you’re saying. The “pyramid” taking up volume and the 30 gallons is all the tank can take because of the poop pyramid.