I HAVE A SECTION OF MAIN SEWER PIPE THAT HAS BEEN INVADED BY TREE ROOTS. THE PLUMBERS SAY THAT I SHOULD REPLACE AT LEAST THE 10-15FT SECTION WHERE THE CLOG IS. WHEN THEY INSTALLED THE CLEANOUT PIPE THEY USED A GREEN PVC PIPE, RUBBER COLLARS AND HOSE CLAMPS. I NEED TO KNOW THE CORRECT SIZE OF PIPE TO GET. I BELIEVE IT WAS 6, BUT WHEN I MEASURE THE EXISTING PIPE IT LOOKS TO BE ABOUT 7.5 ACROSS (THATS EYEBALLING IT). ALSO, IS THE BLACK SEWER PIPE IN THE HOUSE THE SAME DIAMETER AS THE OUTSIDE PIPE? THANKS!!!