Can I sanitize all my large fermentation equipment (buckets, lids, tubes...) by spraying it down with a spray bottle of starsan? Just wondering, because so far I have just been filling the 5+ gallon bucket with starsan solution and sanitizing everything in the bucket. The problem with this is that I feel like it wastes so much starsan, and that stuff isn't exactly cheap.
You can probably achieve adequate sanitation with some very thorough spraying, but the spray from a bottle is not exactly uniform. And I'm not sure how you'd get the inside of tubing effectively besides filling it and sloshing it around, which is certainly an option.
You don't need to dispose of Star-San after using it. You can keep it around for a while, and it will remain effective so long as the pH stays low. Additionally, if you mix it with distilled water, it will last for quite a long time. Months, at least.
You might also find a wallpaper tray to be convenient for sanitizing long items (tubes, canes, spoons, &c.) in a minimal amount of Star-San.
I always have a spray bottle of Star San made up. It's definitely adequate for small items and touch-ups, but I slosh around a gallon of Star San in my carboys since it's easier.
The other thing I do to sanitize some things is to wet a paper towel and then wipe the surface.
The only thing that matters is that you wet all the surfaces and then give it a minute or so to do its thing.
I regularly make very small batches of Star San solution. I use a syringe (not to be confused with a hypodermic needle) to measure out a few mL of concentrate. At this rate my bottle of Star San concentrate is going to last for years.