1:5 ratio of freshly made ginger juice to balance of other ingredients roughly following instructions at Homemade ginger ale is too much ginger. One glass made my stomach hurt.
This recipe doesn't make it quite that strong, but you can increase the ginger as much as you want. It is a different take on ginger ale, and uses lacto-bacteria found in whey to carbonate it. You can make fresh whey (and wonderful cream cheese) from yogurt by wrapping yogurt in a cheese cloth or a dish towel and letting the whey drip out over 24 hours -- How to Make Whey Instructable here.
I prefer this version over the yeast-carbonated ginger ale because the lactic acid gives it a slightly sour bite.
1 small piece of ginger about 1 cubic inch, micro-grated
1/4 cup fresh lemon juice (juice from one lemon)
1/4 cup honey
1/2 tsp sea salt
2 tbsp fresh whey
1 qt. water
Mix everything thoroughly in an air-tight container, and let it sit at room temperature for 3-7 days. You may need to bleed off some CO2 depending on temperature. Refrigerate once it's fully carbonated.
In one batch, after a day at room temperature, I poured the ginger ale into a different container, because I was concerned that the old metal cap on the glass bottle shown in the images would not hold. As it turns out, the plastic cap on the new bottle actually cracked under the pressure! I have since started reusing glass bottles that held carbonated water, which are intended to hold pressure.