Gliders don't need anything added to their water supply, just plain straight water.
If your concerned they aren't drinking do a tent test, pinch the skin on the back of the neck, if the skin stays up like a tent they are dehydrated, if it goes right back down to normal they are not dehydrated.
There are a few reasons for nothing to be added to the water.
1 straight water is better for their kidneys and livers, just like with humans. Adding things to their water makes these organs work harder than they need to.
2 Adding gaterade is only done if and when a glider is definately known to be dehydrated or sick, once hydrated and well it's back to straight water.
3 Adding apple juice or gaterade to a water bottle, might make the ball in the tube stick, preventing any liquids from coming out. So by trying to get them to drink more you maybe cutting off their water supply and not know it. When we add things to their water when they are sick or dehydrated we are usually using a needless syringe, that doesn't have a tube and ball like water dispensers.