I would get a better kit, API isn't the greatest. FWIW I live in limestone country, growing up we had a well, it did clog shower heads every 6-8 months. The main line from the well pump had a gate valve on it with a bad stem packing, if you turned the valve off and back on, it would leak from around the stem but would seal itself back up in a couple days, just from the buildup. It is possible that your alk is that high but your ro/di should be removing that so I would also double check to make sure the membrane is seated properly.