venting

Ok, so here is my issue... I purchased a house a few months ago that is on a septic system. After we were finished with renovations we moved in and started having issues with the system. The toilets would start to gurgle and the shower would start to fill up while in the shower. We thought...

I was told that even though this ties into the main stack, it is not allowed due to it being on a 45 degree angle + it will create a siphon. Is that correct? Additionally, if it is not allowed, there is another vent stack (2") on the other side of the bathroom that I could tie into - not sure...