I've tried differentiating using drip tips as well as small, colored rubber bands.... Drip tips didn't do it, 'cuz I can have 10 or more "working" tanks going (because I'm eternally friggin' FIDDLING around w/DIY recipes) and I like to switch out drip tips a lot and would forget which one was originally on which tank......and the rubber bands didn't work out because I'd accidentally take them off while my brain was in the ether somewhere (talking on phone, etc.).
Soooo.....my solution was,,,,,, :::drum roll::: STICKERS!!!!!! Gosh, I'm so dang smart sometimes, I scare me <grin> . I started out with some of those foil star stickers we used to get on our papers on school, but found that nowadays there are TONS of other options available in itty bitty stickers. I just peel two off a sheet, stick one on my tank and one on the bottle and can always match up what's what.
Coupla notes though, if anyone else wants to try this..... a) wipe tanks/atty//bottle, etc., with iso. alcohol to clean the surface so the label will stick (and even doing this, I've found a couple of types that just won't stick...guess it just depends what labels are made of), and b) If you need to clean or further steep something, put a piece of tape over the sticker so it is less likely to fall off (naturally figured this out after putting 5 bottles at once in the ultrasonic and having not only the stickers fall off, but all my bloody labels denoting content of bottle...AND they were all similar minty/menthol flavors).... DIY is SO much fun. ROFLMAO
Ooops, almost forgot......I also learned that instead of using one of those greasy, citrus type cleaners to get sticker and/or label adhesive residue off bottles, tanks, etc., 91% iso. alcohol works great.