Re: How much line on the casting reel?
YIKES, fluoro for backing,,, that's some pretty expensive backing material
If you think you are going to get to the backing while on a fish, use some fresh 30# mono, if not, just use some old mono off another reel to build up the diameter of the spool.
On my heavy FW trolling reels I put on 10' of 40#mono, 65 and 50# spectra on top of that and then another topshot of 40# mono since I do stand the chance of getting into the backing,,, been spooled before
I use a 20-25 turn albright knot for all spectra/mono terminations as it is a strong low profile knot, never had one of these come un-buttoned. Look up PowerPro's website and they will show you how to tie a modified albright with a lock knot on the spectra tag end. Once the spectra is cinched down tight, I leave a 1/4" tag end and melt that with a lighter to make a ball on the end of the spectra, keeps the spectra from loosening. (FYI, the spectra should wrap around the doubled over mono,,, I think PowerPro's website shows the mono wrapping around the spectra which makes for a bulky albright knot.