Was just trying to help, Once a siphon has started water will seek its own level, Right?
So if the end of the fill hose is below the water level in the resevoir it will continue to flow and you would need some kind of break.
I/my ATO system does not have or need a fitting inline. (still wouldn't trust one not to clog)The end of the hose is higher than the high/full level of the resevoir so siphoning does not continue after pump stops.
However, I re-read the OP and he said it's not a siphon issue. He should check that all his wires are plugged into the correct ports maybe. Then give CoralVue a call.
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