Originally Posted by Tarutan
Hmmm something is not right. I did a 50% water change and ammonia still read at 8.0.
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First, test the tap water on its own for ammonia. Let's dismiss this as a possible source, or not as the case may be.
Second, earlier there was mention of treatments for ich. It is common to have faulty readings, or to have ammonia or nitrite rise, due to the mix of various chemicals such as medications, water conditioners, additives, etc. [Another reason why the less stuff we put in the water, the better.] I don't have the knowledge to sort all this out, but it does occur and needs to be kept in mind.
Third, as long as Prime is being used with each water change, the ammonia is ammonium which is harmless to the fish. And any nitrite will be rendered safe as well. Both will still show in tests, so don't worry over that with Prime. Prime is effective for up to 48 hours, which is why we suggest frequent water changes, every other day should work fine, until these numbers are zero.