09-23-2013, 02:34 PM
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OK that's what I was expecting and an easy explanation for it. The beneficial bacteria use up KH during the nitrogen cycle. In the normal course of things that not usually noticed too much if at all. During a fishless cycle with ammonia it is though. That's because you're building up such a large colony and keeping them well fed and not doing water changes. It happens to everyone, that's why it's recommended to watch the KH during an ammonia fishless cycle (or pH if people don't have a hardness test).
The GH being a little higher is likely from the same no water change period. Your tank evaporates fairly quickly and that was leaving the minerals since only pure water evaporates. Just doing a water top off wouldn't normalize it. My guess is it was even a bit higher before you started doing the small water changes again.