I've tried two batches of cider here in LA, and neither of them came out as drinkable.
I used the same juice for both of them - unfiltered Honeycrisp Apple. It was pasteurized, but unless you go to the orchard and get it straight off the press, you're going to get pasteurized juice. Even when we pressed our own pears, we still had to heat it up to 140 degrees to kill any microbes that might try to take over.
Everything gets sanitized. I use a phosphoric acid based sanitizer, and anything that touches the juice gets cleaned.
So - I filled two three-gallon carboys full of the juice. I used two different strains of yeast - carboy one was White Labs English Cider yeast, and carboy two was a Nottingham Ale yeast. The English Cider yeast tends to eat more sugar than the Nottingham Ale, so you get two distinct flavors out of the batches. When I made the pear cider we used the Nottingham Ale yeast and it came out so good that I had people lined up to buy my entire 5 gallon batch. And it was so good that I told them "Nope, I'm keeping this stuff".
I put the carboy into a bucket. Depending on the amount of pectin in the juice, you can get some quite impressive blow-offs from the gas lock, and putting the carboy into a five gallon bucket helps contain any mess that might come out. It also helps reduce the amount of light that reaches the brew while it's fermenting. So I put the carboy into a bucket, throw a towel around the top to keep light out, and let 'er buck. Specific Gravity at the start was 1.050, so a little high on the beer scale but definitely within the range you want.
Here's the thing. It smelled awesome while it was fermenting. But yeast is very temperature sensitive. Too hot or cold and you get some "off" flavors. And boy howdy did I get some off flavors. The end result was a cross between hard apple cider and vinegar, and even the small sample I tried left me with an upset stomach due to it's harshness. SG was an even 1.000, which puts the Alcohol By Volume at 6.5%. It was just un-drinkable. Too harsh, flavors were horrible, and it upset the stomach.
The only real variable I could not control was the temperature. It's the same with our meads and wines. It's too hot in this house, and the temperature changes too much. There's no real cool place for me to brew and age the stuff. The gas locks never got compromised, the brew did want it was supposed to do, the juice I used was so rich and sweet that I wanted to drink it rather than ferment it, and the yeast was alive and well when I dumped it in. It still turned out crap, just like about half the meads we've made. They've either been too sweet (yeast didn't eat all the sugar), too harsh (off flavors and unpleasant taste from yeast that's too hot), or there's been too many temperature changes throughout the day and the yeast has put out an unpalatable mix of esters that make you gag.
Once I get to a house in a place without this jacked-up climate, or that has a basement where the temperature remains more constant, I think I'll start having success again. But for now, I'm done trying to brew in LA.