Hey all. So my suspicions first arose when I noticed a whole lot of pink coralline showing up. Which was great. The contrast between the two, purple and pink looked quite amazing. However, three days later the pink had turned all white. I suspected lack of calcium since I have added a lot of sps lately. I then proceeded to check my calcium which was 380 quite low for my tank. I tested this 2 days before my weekly water change was due. Normally a constant 450 with reef crystals. I then purchased alkalinity and magnesium tests since I know these 3 go hand in hand. 24hr s after a water change I proceeded to test for the3 parameters mentioned above. On March 30th they were as follows : Calcium 420 Alkalinity 9 Magnesium 1440 All great from what I've read. Right where I want them to be. Then on April 2nd (today) I tested again the results were as follows: Calcium 400 Alkalinity 8.9 Magnesium 1350 All still within range from what I've read. I keep my salinity at a constant 1.026. I've never had to dose anything ever before. I plan on doing another set of tests on Friday. My question is from the data you see will I need to dose magnesium if it keeps declining as it is? And will that keep the other two in check? I apologize if this isn't enough data yet maybe to make an assumption but this is all new to me. Also I have no sump or dosing pumps so any product that anyone has used by adding directly to the DT with great results would be greatly appreciated. Any info at all really would be much appreciated. I'd like to here from some trusted fellow reefers rather than random info on the Internet. I want to nip this issue in the but as soon as possible so I plan on going out this weekend if needed to get some dosing supplements. Also if it helps, I read reef crystals when mixed should have a calcium reading of 500 after I mixed a batch it read 420. Bad batch of salt perhaps? All just speculation. Again any advice would be great. Sorry for the rambling. Been a longggg day.