Seasonal Camping, Trouble with Black Water Tank

[Chevonne]

We have just upgraded to a 39' Jayco 2005 camper. The previous owner had taken out the original camper toilet and installed a regular one. He had the plumbing run right into the ground sewer on his land.
Now that we have it parked on a seasonal camping lot, we bought a 300 gallon black water tank and was told that we could hook it right up.
Unfortunately we are now having issues. Does anyone have knowledge of this set up?

[Billy Bob 66]

A 300 gallon black water tank is much bigger than any black water tank I have seen on an RV. The one on our 5th wheel is 30 gallons. Are you going to bury it or what? A little more info and maybe some one could help.