Im haveing trouble getting my alkalinity to drop below15 dkh. The calcium is up around 560. the magnesium is running a solid 1500. I started with a water change, this didnt help only made the issue worse, turns out my local water supply has naturaly 7 dkh in it to start out with. The solution was to use rodi water. This however has not changed the alkalinity at all. I was told dose more calcium to bring down the alkalinity, however im at the limit were I dont want to take calcium any higher. I Know that Alkalinity plays a part with PH however ph remains stable at 8.4. I really dont know what to do next its been a week sense a 50% water change and nothing has changed. Some of my corals are starting to show signs of stress Im at a lose any help would be great. I should also add that nitrates amonnia and nitrates are all in perfect ranges. This is all according to Sailfert Test kits