I've a 3-tank aeropic septic system with roots growing into the second tank. I've been told to pour rock salt into the cleanout entering the system monthly to kill the roots. Question is whether this salt will eventually exit through the spray field killing all the grass and plants watered by those sprinklers? If so, what do you recommend to kill the roots in the tank without killing all the plants downstream when the processed gray water exits onto landscaping? Thanks!!

Your first task would be to locate and repair the break in the line that's letting the roots into your system. Once you repair the break call around to garden supply stores and ask for fine grain Copper Sulphate. Put a 1/2 pound the pipes of the second tank, By the time it gets to the spray field it should be diluted enough so it won't harm the plants,Good luck Tom