I've not tried Critical Care Formula as I tend to use Reptoboost. I was wondering when Critical Care should be used instead of Reptoboost.
CCF and Reptoboost are different, CCF is a concentrated energy /protein mix for keeping condition on or maintaining energy balance. Reptoboost is an energy drunk with probiotics and some vitamins.
I use them together (not mixed) quite often with Post Hibernation Anorexia, using the Reptoboost to rehydrate and give some energy and using the CCF to halt catabolism of the animals own muscles and reserves.
Its not hard and fast, but I tend to use them on alternate days, not mixed since each is set for a particular dilution.
I use Reptoboost alone for animals which are just a bit slowed up feeding, the bad ones get both. I also use Reptoboost if they are on antibiotics. Reptoboost is also very useful to go in the first drink when tortoises wake from hibernation, just site tem in a warm solution of CCF and let them drink it (remember they also suck it into the cloaca). When you take them out rinse it off the shell with warm water or they will be sticky.