Those are two seperate outlets, one for Ca, and one for alk. Fallback off: tells the outlet to rest in the off state if no other command is controlling the outlet. The OSC command is an on off timer with 4 parts (usefull for various reasons), but the way this one is set up, an easy way to think about it is: off/on/off Then on. This is a very comon way to use OSC, but you could reverse it with "Then Off" whitch would turn it into on/off/on Then Off. The way your post program is set up, they are dosing for 6min 30sec at the top of every hour between the hours of 7pm - 5am for the alk. that would dose 7.15ml every hour for 9 hours = 64.35ml day. The Ca program is similar, but running for a longer period, and during the daytime hours. There is a overide shut off where the alk wont dose if the ph is above 8.2 ( If pH > 8.2 Then OFF). I run a similar program to the alk, but for Kalk. Let me know if you need more help, or I confused you more...