Hi Jim,
Welcome. See below for some answers.
Cheers,
Oliver
aspenjim wrote:I made this today and wondered what it would taste like ... I made this batch 25 liters.
It will be fine. You will find that the body will be a bit thinner than if you had only topped it up to 23 litres. The alcohol content will also be slightly lower and the flavour is "stretched" over more bottles so may not be as flavoursome.
aspenjim wrote:It is 22C and I plan on using a second sachet of coopers yeast in 3 days.
Despite what the instructions say, keep it as close to 18C as you can (the "Lager" comes with an ale yeast, so won't ferment as low temperatures as would a true lager yeast). This will reduce the fruity notes and make the beer more crisp. There's nothing wrong with adding two sachets of yeast, but should add them at the same time, at the start of fermentation. Adding the second sachet later will have negligible effect and is really a bit of a waste of time and yeast. When yeast is pitched to the wort it needs oxygen to multiply, and then starts its anaerobic phase where it works its magic turning sugar into alcohol. Adding another yeast when the fermentation is in full swing really isn't going to do much, although there are times where you may pitch another yeast later in fermentation, particularly for high-gravity beers.
Besides, you need to open the fermenter to add the second yeast and keeping the fermenter closed is advisable, to avoid the risk of airborne infection.
aspenjim wrote:Does anyone ever stir the fermenting brew at any point after pitching yeast and before bottling ?
No. There should be no need, unless you have a stuck fermentation in which case you can rouse the yeast. But I doubt this will be a problem with the beers that you're making. Leave it alone between the time you pitch the yeast and when you bottle, except if you are racking.