I am in the middle of trying this recipe, slightly modified.
I used 8 cans of frozen lemonade (Minute Maid) and a little bit more than 2 pounds of corn sugar, plus 1 tablespoon of yeast nutrient. I'm currently at about 4 gallons and plan to add the other 2 cans with about another 1 gallon total of additional must to bring the batch size up to 5 gallons while giving the yeast time to work without overloading them with acid.
I re-hydrated and pitched Nottingham yeast in an attempt to get a rather neutral yeast profile.
After 24 hours I had ZERO airlock activity. I know, I know, airlock activity isn't a good indicator... whatever, mine work

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Feeling like the yeast wasn't working, I guessed that maybe the environment was a little too acidic for them yeasties to get started. So I re-hydrated some Lalvin EC-1118 Champagne yeast. After it was sort of creamy, I added a little bit of corn sugar and stirred, then let it sit for about 20 minutes. Then I added a little bit more sugar and let it sit again. When I felt like the yeast had probably gotten a good start, I pitched that solution into my carboy.
The next day, I had very good airlock activity. Now, the airlock is rocking and rolling and I can see particles rising and falling (but only on the edge since it's so cloudy). The smell from the airlock is a nice, lemony smell. Pretty much like lemonade.
What concerns me is the "stuff" that's floating on one half of the top of the must(?). It's white, but it's not like any foam I've ever gotten from a beer, cider or mead. It's a lot denser. It seems to me like it could be either pulpy "stuff" from the lemonade mixture, or maybe it's a bacterial infection.
I'm leaning AWAY from the infection due to the smell and the rest of the activity appearing normal, but I was wondering if anyone has encountered an infection while doing a hard lemonade.
If it's infected, how would I know? Would an infection appear like a normal fermentation? The surface of the liquid is fizzy like a normal, active fermentation normally appears to me. Like I said, I can detect no off smells. Would a taste test from a sample tell me what I need to know?
Thanks!!!