What I meant was once a negative voltage is reached, the circuit should perform an action. In this case, I used an op-amp to check the voltage level measure against the reference voltage. The issue was as I changed the reference voltage level on one opamp input, it would effect the measured level on the other input. In other words, the voltage input on the -input effected the +input level. I resolved this feedback issue with a feedback resistor on the -input with a gain of 0.