I could not find a double threaded bulkhead fitting for my Permagreen Ultra spray pressure solution bypass tube. Upper right on tank. I took off tubing and unscrewed the fitting. I inserted a plastic soda straw--into the fitting from underneath. It fit almost perfect. I sealed with hot glue reinforced with a little silicone sealer. Not much pressure here. Used a bendable straw and aimed it to swirl the solution. Screwed it back in and reattched the bypass tube. I will see how it works after I get rid of antifreeze later on this year. May trade it for something a little longer and more substantial. Anybody else tried to set up agitation?