I added 0.77 grams citric acid dissolved in 5 grams water to 234 grams of eGoo.
I diluted with 2500 grams water -- which is WAY gooier than I would normally use. I tend to like a 15:1 water to concentrate ratio.
The pH was about 7.5.
Also dissolved about .75 grams citric acid in around 2 liters of water to have on hand to further dilute the juice if needed. I did not check the pH of that water/citric acid mix.
Outside I spent some time with the diluted eGoo. It was VERY stringy. I made some nice bubbles with a 70" single twine strand top-string loop but it was pretty temperamental.
I diluted it and the juice was awful. I ran inside to grab my pH meter. The pH was 6.3. The film was often breaking prematurely. Making bubbles was very hard. I added baking soda until the pH was back up to 7 and the juice started working very well.
So, 6.3 is definitely too low.
I need to find some time to find the pH at which the juice stops working well.