Off flavor. What did I do wrong?

I have no experience with this product.

I have read from a number of sources that if you use mangoes that are not properly ripened that you will obtain hot/harsh flavors. Using the fruit vs. a processed product does provide more control but you have to use 'good' fruit (mangoes) for the brew.

Cheers!

 

With my tap water (current pH 6.63, alkalinity unknown)...

1/2 strength Star San solution: pH 2.59
full strength Star San solution: pH 2.33

So it appears that at least with some starting water, a 1/2 strength solution of Star San should be effective (i.e. have a below pH 3.0). But I would urge caution. My tap water's current pH is 6.63, but that measurement alone says nothing about its buffering capacity.

 

Just to emphasize my earlier point, and at the risk of being tedious, this would be more compelling to me if there were some advantage to using dilute StarSan. But it is cheap, and full-strength StarSan (that is, 1 oz. per 5 gallons) has no negative effect on the beer. Probably a lot of people could use less than the recommended amount, but why would you want to?

 

I don't think you have an issue, let it carb. I have had several Mango beers and I pick up this underlying trait you are referencing. I think once the beer carbs up it will be ok. I have never had this is a saison, so maybe it is getting amplified. Good luck and reply back once you pop one.