Okay nice, I have a 1 litre spray bottle and some StarSan, how should I mix this up for this spray bottle? Also don't I need to clean (sterilise) it first before sanitising? That's a great idea with the mason jar, thanks!yeah i would spray it down with starsan first. or if thats not an option you could boil a mason jar to sanitize it and use that.
Add 1/4 tsp of Star San and fill to 800mL with water.how should I mix this up for this spray bottle?
You're way off.its 1oz per gallon so if your bottle is a quart then you would need 1/4 oz of star san
And although I don't know how much you can protect against oxygen getting into the head space, I always tip the lid from one side, dip my sanitized measuring cup in, and close the lid as quickly as possible (very gently - minimal splashing). It's probably open about four seconds. I don't delude myself into thinking I've eliminated oxygen, but it's minimized.Regarding oxygen:
Splashing or not, if you open a vessel to take a sample, almost all the oxygen exposure will depend on the amount of headspace in the fermenter.