Hand dosing takes diligence. With my frag tank, I tend to forget about it and missed a few doses. Needless to say my levels were not as stable as they should've been and I had a couple of SPS STN on me.
I finally just ended up buying a marine color dosing pump for the frag tank so I don't worry anymore.....except when I forget to refill my calcium ... like last night! I think I caught the bucket in time though as there was about an inch left in my 1 gallon container. I gotta check my calcium tonight though, but I think I caught it just in the nick of time as calcium was still in the peristalic calcium pump =) lol.