Under-diluted Starsan

Searched everywhere and couldn't find anything. Is underdiluted starsan a problem? Ever? Say you throw a capfuls worth into a spray bottle. Besides wasting starsan, will an ultra low pH, over concentrated starsan mixture do anything other than kill microorganisms? Will it be ineffective at all? Will it contribute off flavors? If so what?

Interesting question. I do wonder the best way to measure starsan for my spray bottle without small measuring instruments.

I usually make 5 gallons worth for pushing through kegs and just fill my bottle from there.

Star San is actually pretty simple stuff, an acid to fry the bugs, and an agent that encourages wetting and prolonged contact.
If you mix it stronger than recommended you're just using more than needed.
But it will definitely work - there's absolutely nothing contraindicative...

Cheers!

I contacted Five Star a couple of weeks ago about this. I was told there is a limit of 200 ppm, and pH no lower than 3. The limits are based on 1) Corrosive to bare hands and 2) Preventing off flavors, assuming it is not rinsed. By my calculations, the ppm limit doesn't make sense, but apparently there is a limit. I settled on a 1.2 factor, but that's really a guess.

the ppm limit is based on the goal of getting to a pH of 3. (you want the whole chemistry reason/math? no didn't think so)

Probably experience says a pH lower than 3 is irritating to humans, and they know despite the warning a lot of us don't glove up. In the same fashion they've probably notice that over 200ppm there is the ablity to detect the flavor left on the vessel. - I'm not sure that this is always true, because on a volume basis, a wine glass has a lot more surface, and therefore a lot more chemical left behind than a 6.5 gallon carboy would.

But they are selling a product and want no complaints. So first they figure 'what is needed to get the job done' (pH of 3) and then error on the side of get as close to that as possible.

On a side note (back to the chemistry), without working it out by hand the shift from pH 3 to pH 2 should be a factor of 10 in the amount of chemical needed. pH is short for negative power of Hydrogen, and is a measure of the amount of free Hydrogen atoms in the solution which are looking for a molecule to bond with.... which is a long way to say if you are going about 2x what is recommended, you won't have that much more pH power, and are ok. Just wasteful.

I do know it lasts a lot longer when mixed up when I use RO water to mix it with... otherwise its no good in a short period of time as the ph rises above the effective level.

In addition to a Starsan spray bottle, I like to have a small 1/2 gallon bucket around, like those from Margarita mix, half filled with Starsan. I keep a couple small cotton wash cloths in there for mopping Starsan around bucket lids, wiping rims, hoses, insides of buckets, around air locks, necks of yeast starter flasks, filling air locks, etc.

I also prefer to have a larger, 3-4 gallon bucket with Starsan around to dunk pieces of equipment in during brew day, racking day, yeast handling, kegging, bottling, etc.

You could use a 10-20ml plastic syringe to dispense 5.6 - 6 ml of concentrate into a gallon of water. A 10% measuring error should not have any impact, given the geometry and precision of their 16 and 32oz dispenser bottle.

Save the working solution you don't use in a jug for next time. If you use RO or distilled water it is supposed to not become cloudy, although I've never had any trouble using it when it does becomes cloudy, which happens usually after 2 days. I use regular de-chlorinated tap water.

Similar to IslandLizard I have some of these to measure Star San with: 10 Pack of 10ml 10cc 2 Tsp. Slip Tip Oral Medication Syringes

I think it is 2 ml per quart (sprayer bottle) and 6 ml per gallon.
I also keep 2-3 gallons of it mixed in RO water in a bucket that I dip things into on brew day and change out every couple of brews.

mcgimpkins said:

Similar to IslandLizard I have some of these to measure Star San with: 10 Pack of 10ml 10cc 2 Tsp. Slip Tip Oral Medication Syringes

I think it is 2 ml per quart (sprayer bottle) and 6 ml per gallon.
I also keep 2-3 gallons of it mixed in RO water in a bucket that I dip things into on brew day and change out every couple of brews.

Click to expand...

That should be around 1.4-1.5 ml per quart, not 2 ml.

I still don't think it makes sense to mix less than 1/2 a gallon though, using 2.8 - 3.0 ml of concentrate. You can buy 3 ml syringes, which are also great for hop shots.