For my carboys, I usually just use about a cup and shake/swirl the carboy for a few minutes to ensure the star san covers the entire surface area for 30ish seconds. Then I pour it as much as I can back into my star san bucket. Seems to work well so far.
Yes I almost always use a spray bottle exclusively to sanitize. Carboys are the exception because it’s not easy to get a good coat on the upper interior with a spray (at least for me). I make a cup or so of solution and pour it in the carboy and shake it up until everything appears well coated. When I pour out the excess solution I capture it in a plastic bowl and use it to sanitize small parts or add it to my spray bottle.
Its a very GOOD spritzing, ending with about a half-inch of Star San on the bottom. Make sure you get the lid, inside the grommet, etc.
I am a bad example, though. I’ve only brewed mixed-fermentation beers over the last year. I definitely have had cross-contamination, but its quite welcome
I have a 2.5 gal keg filled with Star San for filling spray bottles and sanitizing kegs, lines, transfer tubing, glasses, and fermentors. If I need the keg, I just fill all the spray bottles and dump.
I use a spray bottle to sanitize everything. I mix up 1 gallon at a time using distilled water and fill my spray bottle as needed from the one gallon jug. For kegs and carboys I just make sure to give it a good sparyaing and then swirl it around to make sure it gets up at the top.
I soak tubing and small items in my 5 gallon bucket of starsan. Since I ferment in buckets I pour the bucket of sanitizer into the fermenter bucket, put the lid on and swirl like hell, and pour back a couple minutes later. I then use the spray bottle for any needed spot sanitizing, like on the bucket lid, grommet, keg posts and QDs, etc.
I use a 2 gallon veggie sprayer, the kind you would use to spray pesticide(it was brand new and has only had san star in it) I like it cause once it is pumped up you just pull the handle, instead of having to squeeze a spray bottle a thousand times. They are made to handle some caustic stuff so I have never had issue with it leaking or corroding.
The solution in the old windex bottle is eight-ish years old from the first bottle of Starsan. Clear as the day I made it. I’m on my second bottle of Starsan now and mix it into an 1L PET (soda) with my RO water. I think it’s like 1/2oz of SS per litre. Keeps forever that way.
I’ve only ever used the gallon jugs (star san directly into distilled water) and spray bottles (from the jug). I typically pour maybe 1/5th of the jug into the carboy and shake. All the smaller components get a shower from the bottle. I haven’t had any holes in my gallon jugs though.
Yeah, our tap (well) water has 380 ppm TDS. Star San goes cloudy instantly in it and probably the PH goes wrong (and I think PH is how SS kills bugs).
I use RO water (16 ppm TDS) from the machine at WallyMart (37 cents/gal.) and store the SS mix in gallon glass jugs. Keeps for months at least.