Ok, My main line is not draining properly. I have had two different plumbers come out and snake the line. The line works fine for a couple of days then the problem starts all over again. All the lines drain into the main just fine, except when I run my washing machine my toilet empties and I hear a gurgling sound. One plumber says my 90 at the end of the line is about to collapse(no camera was used either), but the other just says it was a tree roots and recommended copper sulfate to kill the roots. I have used the copper sulfate, several kinds of acid, I even tried a garden hose with one of those expanding rubber ends to force it out. What is going on with my plumbing?

Pay to have a camera run through it to the street... it will tell you a lot more since you have already tried having it snaked a few times... that way there is more knowing and less guessing about what might be at fault.

when I run my washing machine my toilet empties and I hear a gurgling sound. You have a blocked vent that must be snaked. Check and clear the washer vent, While Copper Suppurate will kill the roots it won't dissolve them. You're left with a tangle of dead roots that must be cleared with a sewer snake with a cutter tip. So. Snake the vent first with a auger tip and then the sewer line with a cutter tip. Good luck, Tom