Maybe more than one problem
First, check the joke valve in the toilet and replace if the "lips" aren't closed.The Atlantes comes with a # C254 joker valve, black in color, with cross slits in an "X" pattern. Replace it with a # C253, red in color, with the traditional "duckbill" single slit design...that style seals much better against backflow. There's also a good chance that your Lectra/San is clogged. It MUST be run with every flush of the toilet - don't try to cheat the system by only running it every now and then...unless everything in it gets macerated thoroughly, it'll develop a clog. That prob'ly isn't air coming out the Lectra/San discharge thru-hull when the toilet is running. The L/S discharges by overflowing and can only discharge when the toilet is flushing...As the toilet is discharging from the bowl, the incoming pushes the same amount out of the Lectra/San. Air can be drawn into the toilet bowl during the "dry flush" cycle, but the "bubbling back through the bowl" usually is caused by something trapped in the macerator (paper towel, handy-wipe, other feminine products, etc.). Usually, flushing the toilet a dozen times or so will clear it--that is, IF the L/S isn't clogged. Often, if too much paper is flushed at a time, air can bubble back from the bottom of the toilet bowl. There could possibly be something caught in the joker valve (fair chance) that is holding it open from sealing - cigarette filters are notorious for that. So start trouble-shooting by first checking the joker valve in the toilet...remove the fitting at the rear of the head where the large discharge hose connects...leave the hosestill attached. Be prepared, though...if the discharge line is pressurized due to a clog you could get a nasty shower. Check the joker valve to be sure it isn't clogged with any "stuff" and that nothing's caught in the slit. Next, as long as you have the head is pulled away from the wall anyway, check the clear plastic (oval shaped) cover plate over the macerator and discharge pump. If anything's caught in there, it is usually visible through the clear cover. Remove the cover and pull the offending matter out with needle nose pliers. Then replace the cover - "O" ring seal is reusable, just don't over-tighten the screws that mount the cover. Finally, be sure the Lectra/San isn't clogged with who knows what, by CAREFULLY removing the removable plug on the center stack of the Lectra/San and poking a screw driver inside to free up any clog. If there IS a clog it will be in the center stack area of the treatment unit. The unwanted shower caution also applies here, thus the mention of doing it carefully. While you have the discharge fitting off the toilet, check the inside of the hose for any calcium buildup that may have reduced the diameter enough to restrict the flow. And finally, read your owners manuals for both the toilet AND the Lectra/San. Most problems can be prevented by making sure to operate and maintain equipment according to the directions.
