I am attempting to preserve the shelf life of ice tea up to six months with citric acid, I need a perfected ratio?
If the tea was distilled water, a 5% solution would have been sufficient. That is, you'd need 50 grams of acid to 950 grams of water. The problem is, the impurities of the water and the tea itself buffer it somewhat, so it's impossible to predict the exact amount you need. You'll have to use a pH meter, and an accurate one, not strips, to make a pH solution at 1.8 or below. And then hope than you don't have high-acid liking mold around. 

The problem is, at this concentration, tea will taste more sour than pure lemon juice, in fact it will have to be more acidic than your own gastric juice. Drinking it will feel like having heartburn all the way from the mouth to the stomach. 

My suggestion: ditch the whole project. Tea is not a shelf stable product. Trying to invent home methods for food preservation is dangerous, you were lucky that mold is visible. You'll have to step your tea fresh.