Skunk smell after pee in diapers

Does anybody know why my diapers smell like a skunk after my daughter (8 mo) pees in them?

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We had this problem about 2 months ago. I did some research and thought I was using too much detergent (and I had read the Tide packaging wrong so I definitely was using too much detergent). I stripped with blue dawn in the bath tub, washed everything a million times with just water in the washing machine, and the problem did seem to be fixed... for about a month and a half. Now the smell is back. I used an online calculator to determine how much detergent I should be using this time -- is it possible I am STILL using too much? Could there be another cause? And do I need to strip again now??

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Wash routing is cold rinse, then warm wash with Tide powder (up to the second line). Our water is hard but when I looked it up it seemed like it was within the parameters of what Tide powder can handle.