Calc and Alk for sure, I'm using about 1 DKH ALK a day, I keep a lot of sps.
Also started dosing some Iodine this week (thanks Dong), because I can't seem to keep xenia from melting (Dong that xenia you gave me melted in two days).
I want to start dosing balling salts, but have been having a hard time locating a source. Right now I am just dripping Kalk. mY demand is pretty low, I only have ~20 or so 2 inc frags in my stick forrest. lol
I use SeaChem Advantage Calcium and Reef Builder alk, both powder. 120g of calc and 180g of alk per liter. I mix it with RODI water and put it in 1 liter Bendix bottles for squeezing and measuring. 60ml of calc and 100ml of alk daily. A lot more cost effective than pre-made liquids and I trust SeaChem much more than that 'bulk" stuff.