I have my 75g (100g total) 2 month old setup and my alk keeps dropping to 6.5 according to Hanna. Using reef crystals, when mixed to 1.025, alk is 10.9. Doing 10g change per week. Started with dry rock and Carib sea live sand. Calcium stays about 450-500 mag almost 1500. Have 2 clowns and a couple small corals. What would be dropping the alk every week and is this something I need to start raising?