Can't stop water flow

[ByJove]

Just moved into a place that has a salt water pool and the equipment is a foot or two little below pool level. Trying to clean the Intellichlor ic40 but can't get the water flow to abate. I've closed the diverter in front of the pump and there are two check valves in line after it and before the ic40. I've emptied 25+ gallons with no end in site. The pool filter still feels to be completely fool, if the water's coming from there. If it's not, I have no idea where it comes from or how to stop it.

I assume I'm missing something. Any help appreciated.