Ok, I have not checked it in at least a week. I am going to take a sample to the LFS tomorrow and see what reading they get . I did a 5 gallon water change last week. I usually don't do that much at one time but I wanted to move the rocks around a little and clean the sand a little better. Plus I had some small rocks I put in with the live sand , I thought it looked nice with a variety of size in the substrate. I decided I didn't like it like that and sifted the sand to remove the the larger sized rocks out of the substrate and leave just the sand. I also vacuumed the sump in the back of the tank. I don't knowif that had anything to do with the drop. It was at about 9 a few weeks ago when it was checked. It says on the back of the alkalinity buffer bottle that for coral growth you need it at 12.6 dkh.
