What pressure to Ale yest stop?

I am trying to think of a way to carbonate my lemonaid that wont involve letting it ferment all the way out, because if I do it will be VERY dry, I hear that usual FG's are in the 0.9xx-1.005 range...

I want to bottle it at about 1.020 FG, which will leave the yeast with to much food to eat. I want to bottle it in 2 liter soda bottles which I know can hold around 100 PSI safely, so the question is when will ale yeast stop fermenting and is this safe to do?

Thanks

The only way I know of to (maybe) halt a ferment is to use campden tablets (1 per gallon) and pottasium sorbate (2/3 tsp per 5 gallons).

It doesn't always work- especially if you used an alcohol tolerate yeast like champange yeast. So, what I would do: (and have done, but last summer, not recently)- Add the chemicals as above, by racking unto them after you dissolve them. Check the s.g. Wait 3-4 days and check the s.g. again- if it's the same, it's safe to bottle or keg.

The problem- you can't carbonate it after you kill the yeast this way, unless you are kegging. Also- it doesn't always work. Lemonade is a bugger to start, but doesn't ever want to stop!

Last option is to wait until fermentation is done (it will be too dry). Then use the sorbate and campden as above, wait 3 days, then sweeten to your desired taste. That WILL work, but again, you can't carbonate it unless you force carbonate.

Or.....let it finish dry. Add lactose to sweeten. Then add 1 tsp. sugar to each 15 ounce bottle. Then you'll have sweetened, carbonated hard lemonade.

I dont want to stop them though... I want to use them to carbonate it at the end, so bottle when the gravity is at about 20 points, wait a few days for pressure to build and for it to carbonate, then refrigerate it to stop the yeast. Only dissadvantage I can think of is if they ever get warm again lol.

But I recently read that yeast cant work under high pressure, and if that pressure is below 100 PSI then I am safe to just bottle whenever into plastic soda bottles because the yeast will stop working before they can build enough pressure to overload the bottle.

I want to know what PSI normal ale yeast can handle to see if my theroey would actually work.

No, it takes more pressure than a cornie or a soda bottle can handle to stop the yeast.

So why not add lactose right from the start, let the yeast attenuate fully, and you should be left with a higher FG.

I actually didnt think about that, I did however buy some splenda, that I will add when I bottle it along with the blueberry concentrate to taste...