I have a nitrate (sulphur) reactor I have been running for a while. I used to monitor it with an ORP probe via a Digital Aquatics Archon controller which had no problem reading a negative ORP reading. Now that I switched to the Apex 2016, I cannot get a reading. I made a crossover cable (2 of them actually) but it only reads 0. I have tried connecting through a PM1 as well as directly to the brain but same result.
Can someone help me out with this?

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