Fizzy kraut and brine

[millefolium]

I have a batch of sauerkraut on it's 9th day of fermentation, at about 60 degrees, in a 2 gallon crock. It's a mix of cabbage, lemon juice, fresh garlic and dill, and salt. It's becoming sour - partly because of the lemon - but I'm noticing there is a fizzy, almost carbonated quality when I taste it. It's pretty crunchy now, but seems like it's heading toward getting soft. I live is a damp climate and there is mold forming on the bottom outside of the crock (I wipe off daily). Is my kraut contaminated?? Is the fizziness normal, or is it an indication of something going wrong? Maybe I need more salt in the brine?