Varied readings over a couple days

I have a KH director that has been set up for about two weeks. At first the readings would slowly drop one to two dKh per reading. It would start at 10 and then over a couple days drop to 6. With a Red Sea test kit i get 7.8 fairly consistently. I decreased the ml/minute of the waste water pump hoping to clear the test chamber better. Got a reading of 10 again and then dropped more quickly. Is there some area i should focus on first or do I need to remeasure and recalibrate everything?

For the past two days I get 8.3 dkh in the morning and 6.6 twelve hours later. I dose alkalinity with a doser that is done 5 times a day over a 24 hour period.