ok so let me sum this up, there is no carbon source that will be used in this tank. Only the big skimmer, some LR and the RDSB and the refugium. CA and ALK will be taken care of by the grotec which will also dose trace elements? How often will you be doing water changes Leonardo and how are you going to stop corraline algae from growing in your skimmer as you will have the Refugium lit? Thats a problem i currently have. reason i am asking is because i want to run my tank exactly like you but i want to have a big crypic zone filled with LR about 20 to 30kg(will be prefiltered to ensure no or very little detritus gets in),want to also grow algea some cheato and calurpera, dont want to make the solutions for the balling method as i want to use a CARX any specific reason why u no longer using the CARX?