[2airishuman]

hi mathewsim and,

holy crap!

also welcome to the forums....

IF you are leaving the black tank always open to drain,

then you've got a poopy teepee growing right under the drop zone...

like a giant cherry mash!

if however you are correctly draining the black tank only when full and along with adequate fluids...

it could just be a paper plug...

before calling the suction tanker guys (a good idea) try this...

2 approaches to this issue,

into the mouth of the beast or at the exit...

wearing gloves and a mask or bandana and using a 10 foot section of old garden hose...

shove said hose down from above into the tank, push at least 8 feet in...

then rotate, agitate and other wise wiggle d' hose...

now open the black tank valve...any movement?

if not carry the hose outside and run'r up the drain valve with only the black tank open...

again agitate AND ya might want to wear high water boots for this step...

this will open up all but the most hardened coprolites...

please take some pics, we need a little humor this week...

and it seems i've misplaced my photos...

cheers
2air'