my Aqua C sits above my sump, my discharge is above the water line so there is no siphon, I'm using a gen-X pump, cut back a bit with a ball valve. my water level in sump is constant, zero fluctuation. thanks for the help,, i had already made the adjustments you are talking about,i cut back the airflow and readjusted pump and it seems to be working fine now for about 24 hours so we will se what happens.. i placed nothing in tank to make it go crazy and all livestock is accounted for,, i do believe i now know what happened though.. i had just cleaned it and gotten it back on line with air valve open 100%... when it Kicked in it was producing LARGE bubbles and too much air was forcing it all out the top... and of course i had just left for work,,, heres a good tip never adjust equipment unless you will be around to monitor it for proper function afterwards ...we should be good now