for me, I don't use a sinking line for streams if using nymphs unless im high sticking. I like to use a floating line and a Indicator, but i will use weighted flies, and/or split shot spaced out on the lower end of the line to get it down. For streamers i might use a Sink tip like a 5.5-6.5 IPS . But most of the moving water i flyfish don't require it. Sometimes im even to lazy to switch out my reel's Spool , and just add split shot But thats just me, others will have thier own preferences.