I tell people to use half-strength. That doesn't mean you can't use some things full strength, but don't go double strength :P I always tell people to use half strength because it's so safe and most Nepenthes don't get a butt load of light (light and nutrients go hand in hand. If you have a lot of one, you need a lot of the other!) since they're shade tolerant, anyway. You can't mess that up half strength, though.