We have used liquid plumber. We have snaked out the clean out and the toilet. We took toilet off and snaked it. We got on the roof and nothing in the vent. We have septic tanks which were cleaned out 2 yrs ago.

Hearing bubbling in the tub What you're hearing is a "gurgle" which is the sound of air being drawn through the tubs trap. And all this is caused by a blocked roof vent. Go back and snake the vents again. Put out enough snake to reach the base and 16 feet more. Good luck, Tom