acidic sauerkraut

[angelfox]

I made some sauerkraut with spices and apples,
and when I looked at my batch yesterday after it had rested for about a week , it had green/blue mold on the surface wich I read was due to not enough salt... but it is not a problem right? I tend to try to reduce salt as I seem to eat quite a lot of sauerkraut and I don't want to eat too much salt...
but to come back to my sauerkraut it was fizzy and quite acidic... (not so good), any idea why? is the fizzyness due to the apples fermenting? can it improve with time the taste? the acidic taste?
thank you