Yesterday my toilet did something weird--after a normal flush it did not refill all the way (fills a couple of inches only,) the water took on a slightly dark/grey tint (still clear) and there was black dirt/grit settled in the bottom of the bowl. I flushed a few times to see what would happen. Gradually the darkness and dirt cleared, but the issue remained, the toilet flushed without a problem but the bowl would only fill a few inches.
Strangely, the tank's filling and emptying appears normal when compared to my other toilet, and we can get the bowl to fill by holding the flusher down after a flush. It fills to slightly more than normal then drains to normal. But then on the next flush, if the flusher is not held, the bowl does not fill again.
Any ideas would be appreciated!