@mn_booner - All knots reduce the strength of the rope. Some knots do so more than others. One of the knots that reduces the strength of the rope the least, is the figure 8. I was taught to use this as the tie-in for my rock climbing ropes from a professional rock climbing instructor.
Link:
Figure 8 Loop - Animated Knots
I also leave the tag end long enough to put a fisherman's stopper knot in place as an extra measure of safety. The knot can be neatly tightened (or "dressed") a little better than in my photo here, but this shows you what it looks like. It will tighten and get smaller once it's been weighted.
View attachment 33707
P.S. Here's a link to some data on how big of a strength reduction you get for various knots in different ropes that were tested:
Rope knots: Strength Loss