Set the grape juice out to thaw, until slushy. Mix the sugar thoroughly in with the grape juice. Pour the sugar and juice, into the gallon jug. Dissolve the yeast in a cup of lukewarm water and add to the juice mixture in the gallon jug. Mix completely. Now add just enough lukewarm water to to make about 4 gallons. Use the fish tank air hose and a mason jar to make an airlock. You need a cork with a hole in the middle for the airline, that fits the jug and a mason jar with a dome and ring. The dome needs to have a hole punched in it for the airline. The airline should not touch the liquid in the jug but should be submerged in about 3 inches of water in the jar. As the wine ferments , the airline will release bubbles into the water in the jar. You want a slow steady stream of bubbles. If it's bubbling like crazy the wine is to warm. If it is barely bubbling, it's to cold. Bubbling will slow or stop when wine is done. You can add more sugar and referment the wine or sweeten it if you wish. Store the mixture in a cool area (60 to 75 degrees Fahrenheit is ideal) for a period of 3 to 6 weeks. Check the bubbles every other day. When the bubbles cease, the wine is done. You can add more sugar now and referment the wine. Warning: If you bottle this wine before it is done fermenting the bottles may explode from excessive pressure. They make Champagne by adding extra sugar at this point and letting it ferment in the bottle with a tight cap. This creates the bubbles. Champagne bottles are thicker than regular wine bottles to take the added pressure without bursting. Siphon the wine into clean, strong wine bottles, using the airline. Leave any sediment in the jug. You can syphon the wine into a container, straining your wine with a cheese cloth or a tea towel and pour into bottles if you wish. Cap or cork bottles and store on their sides in a cool, dark place.