I have a question pertaining to total dissolved solids(TDS). The chemical companies literature says once it's >1500 it's time for a water change and the spa mfg and spa shop say when it's >2500 it's time for a change. I've spent hours upon hours reading this forum and see very little mentioned about it at all, plus my Taylor test kit doesn't mention it either. So I'm wondering how important is it really, if at all? I plan on changing my water every 3-4 months no matter what. So, is this something I even need to think about? Let me know your opinions.