I wish I had much to give you on information but I had experience with Micromhos type Conductivity readers. As I understand it, Micromhos is more accurate and give the true value of conductivity.
What type of water system do you use? closed system? It appears that perhaps the ink is being emulsified meaning it is too hot or too much Fountain solution. It has been 15 years since I did any test. I use an dosantron system to mix % of fountain solution and water. I just had to figure the % using a tester when it was first put in. I do know that according to the instructions of the Fountain Solution, it will say, to start out at (something like) 2 oz per gallon. But you may not have the system to know the ratio.
Thats my two cents.. and hope you find an solution