From what I've been reading, it appears if one has a spring fed pond with water coming in and out, lime and/or other chemicals might not last long. Especially so if the water is very soft. Am I correct in this assumption?
Depends on how much flow you are getting. A nice little spring can change your water 100% every 2-3 days. That would also depend on the shape of the pond and entry/exit. Whether the spring has hard or soft water, the pond water will be almost identical.
If your pond fills up and over flows from runoff, that will change the water too... and there goes your chemicals.
