I want to carb up my cider and Im wondering if I can use DME ? Ive got about 3 1/2 to 4 gallons, so what would be the correct amount to use ?
Depends on how sparkling you want it. I use regular corn sugar and carbonate to 2.5 volumes. That is .72 ounces per gallon. Look up http://www.tastybrew.com/calculators/priming.html a handy calculator that will answer your questions.
Dunno how much, but any fermentable sugar can be used to carbonate so give it a blast and let us know how it goes