GW, is there a vent hole in the uppermost part of your siphon to allow the air trapped inside the highest part of the pipe to escape? It also appears that you do not have a trap at the discharge end. The trap isn't 100% necessary but it helps. Please describe how your setup is different than the drawing shown here http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=99802&fpart=2



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