Brew Tips: Cloudy StarSan

This will be a very quick post to clear up a common misconception: cloudy StarSan does not mean ineffective StarSan.  StarSan, made by Five Star Chemicals, is my favorite sanitizer.  Its cheap, easy to use, and doesn’t need to be rinsed off before use.  It even makes a yeast nutrient when diluted, like when wort is added to the fermentor (don’t fear the foam!).  It also has a tendency to get cloudy when its left for a while after mixing with water.


Starsan sanitizer from 5-Star Chemicals

StarSan is an acid based sanitizer which is effective when the pH is 3.0 or below, and is designed to be well below this when properly mixed (I think something like 2.5-3 or so?).  The problem is alkalinity in the water which can slowly neutralize the acid.  Most people think that the cloudiness is from the pH raising above 3, signifying ineffectiveness.

Unless you have extremely alkaline water, this is probably not happening.  Instead, the cloudiness is actually from a surfactant in the StarSan, Dodecylbenzenesulfonic Acid (DBSA), clumping up and coming out of solution, causing a haze (sort of like protein haze in a beer is caused by a proteins and tannins complexing and clumping).  To stop this from happening, I have heard of people storing StarSan mixed with distilled water in a closed container (like a spray bottle) basically indefinitely.  [2014.01.25 UPDATE: The surfactant is especially prone to coming out of solution and complexing with iron or some other metals in the water, if present, and forming a haze.]

As long as the pH remains below 3, the solution is still effective as a sanitizer, regardless of haze.  [2014.01.25 UPDATE: There are two active ingredients in StarSan: DBSA and phosphoric acid.  DBSA is really the active ingredient: it cleaves through cell walls and kills bacteria and fungi.  Phosphoric acid is added to keep the pH low enough for the DBSA to do its job; if the pH is too high, the DBSA cannot interact with the cell walls.  For more information on how StarSan works, I recommend this Sunday Session show on the Brewing Network, an interview with the StarSan creator Charlie Talley.]

– Dennis
Life, Fermented


About Dennis
Home brewer, home chef, garage tinkerer. Author of Life Fermented blog.

5 Responses to Brew Tips: Cloudy StarSan

  1. Jon D. says:

    Finding this post on Star San just now was quite interesting in that I was just discussing this product at my club meeting this week. I’m fairly new to home brewing so I ask lots of questions and read anything I can find (when time allows). The question of viability was discussed and it was suggested by another member that I consider quite knowledgeable, that the pH should be in the 2.5 range. My Star San, when diluted as directed, comes out at 3.5 with my tap water (pH-7.4 to 7.6). A little worried, I called the people that make Star San and they told me anything at 3.5 or lower is viable.

    • Dennis says:

      This is definitely one of those hobbies in which you should never stop asking questions! I have always heard a pH of 2-3 is ideal. This is from interviews of various Five Star chemists over the years on shows on the The Brewing Network– including at least one with the creator of StarSan. If memory serves, there was one Brew Strong episode in all of their archives and two Sunday Session shows up to late 2006 (as far as I have gotten through the archives so far) with actual Five Star people, and maybe another few shows sprinkled in about sanitation in general (see my post updates from 25 Jan 14 above).

      That said, if you called and they told you 3.5, I think you are fine. If you are still nervous, you can probably get away with adding a touch more, but don’t go overboard- too low of a pH is also bad.

      I would also check whatever measurement method you are using. pH meters need to be properly stored, maintained, and calibrated, while pH paper is not very accurate (colorpHast, one of the better brands as far as I know, was investigated here and found to be regularly 0.3 low; other brands can be +/- 0.5 or greater).

      As a sanity check, try mixing the StarSan with distilled water to see what you get. Your water, even at a relatively low pH, might be very high in alkalinity. This alkalinity will react with the phosphoric acid and result in a higher than ideal pH for the StarSan mix. You should be able to find a water report or use a $5 aquarium test kit to find this out. If this is the case, you should also take great care to ensure your mash pH (if you are an all-grain brewer) is in the proper range.

      – Dennis

      • Jon D. says:

        Thanks for the quick response. I did just make a fresh brew so I had my pH meter out and freshly calibrated, so before putting away all my equipment I did the test on the Star San just to see. That’s when I discovered the higher than expected reading. I have a small under-sink RO filter and in the future I think I will use that, at least in part, to see if I can keep the pH down a little more. It will make me feel more comfortable that I’ve santized everything properly.
        My water report from the city has my bicarbinates at 244 ppm and that’s just an average. With the drout we’re experiencing here in California it’s probably up even higher since we’re on auquifer water.

      • Dennis says:

        Ah, that is almost certainly your problem then. The RO is probably the best option. You could also try just acidifying your water to knock down the alkalinity- just about any food grade acid should do the trick. 1 mL/ gal 88% lactic will knock down your bicarb by 185 ppm, or 10 mL/ gal 10% phosphoric will give you a reduction of 180 ppm. That should pull it down plenty to let the StarSan do its work. I’m not 100% sure of the interaction of a different acid with DBSA, so you might want to stick with extra phosphoric just to be safe.
        – Dennis

  2. Anonymous says:

    Glad I found this post. Thanks!

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