I 've asked this question on many forums and it never gets answered My system: about 2 years old 93gl cube with 40gl sump about 20 sps T5 8x80w Ati Tunze 9430 Skimmer 2 Maxspec Gyres Good stable conditions Weekly 10% W/C Ca 450 Alk 9.6 Mg 1370 about 4 months ago switched from ESV 2 part to ** 3 part. All the coralline stopped...started Kalk in the ATO it came back for a while but died off again. I also have 2 friends with a 575gl and a 60gl systeme ,same story. Am I missing something? Cause I'm about to go back to ESV 2 part.