Hello everyone! I recently bought the Apex system and I have an ORP probe that I need to swap out for a 2nd pH probe rather than having a ORP probe. I want to sell the ORP. It's brand new and I can sell it for $85. Lab grade goes for $90. Please don't ask for lower price because like I said it's brand new not been used. I was under the impression that you could use the ORP probe as a pH probe and that is not the case and do I feel dumb 
Please let me know and thank you.
Please let me know and thank you.