i wouldnt worry about it to much..whatch that favia..it will tell you if its unhappy..but try to keep it around 400..i was thinking i read something about people having bio cubes having an issue with keeping their calcium levels up somewhere but i cant remember where it was as it was a long time ago and im getting old...lol.. Rob is right if you can find one get a mag test kit and test for that..i dont dose mag because of the big water change i do, that and i cant find a test kit either and im afraid to dose it.

Rick