It is my understanding that corals use alkalinty and other elements to make their skeletons. So, in theory the alkalinity in my tank should be going down due to my corals absorbing it, right? I tested my water two days ago and the alk was 8.7 and today it is 8.9. Is there any explanation for this? I’m using a hanna checker and the accuracy is .01 ppm I believe, so maybe it’s the checker, but I’m not sure.