Another minor point- Emergen-C powder packets are not really electrolytes- they contain mostly vitamins. The same company however DOES make packets with specifically electrolytes content for replacing those lost during exercise.

I use both. The electrolyte powder directions say one packet per liter- so I mix up a liter of water with one packet and divide it into 3 water bottles and keep them in the fridge for my bike rides. I use about one per day. The Emergen-C packet (which says one packet per glass of water) I either throw into a water bottle just before I leave (vitamin C does not store/stand well), or I drink one in a glass of water later in the day.

Aside from the 1000mg of vitamin C in the packet of Emergen-C, the other vitamins in it are not very strong at all, and if as you say you are drinking "very diluted" Emergen-C water, that probably isn't doing much in terms of any nutrient replacement.
FWIW....here is the electrolyte powder packets I use that are made by the Emergen-C people:
http://www.allstarhealth.com/f/alacer-electro_mix.htm
You mix one packet to a liter of water (NOT one packet per water bottle!)