I wonder if I should buy one of those bead knotter tools?
There are people who swear by those knotter tools. Personally I think they are useless. I got one free from a friend who hated it. I notice quite a few people bought them and the video, and never learned it either and leave them lying around in hopes of finding someone who will take it. It really interrupts the rhythm of knotting when you have to pick up a tool to deliver the knot-either a knotter or an awl or other instrument, then put it down, then pick it up, etc for each bead.
A double strand of stringing material, a needle and just your fingers make the best knots.
I don't think silk is necessarily the best stringing material for beginners- neither is any other kind of thread with a twist, like Griffon or Detulon. The latter especially, coils up into little tiny loops if you don't keep letting it unwind between knots.
About the gaps. The reason I go through 3 beads is to place two knots after the clasp, then "hide" the end of the string in the third bead.
A trick I use all through the knotting is to pull the knot tight. Tight. Then try to stretch it with a hard pull. Any kinks and knots will disclose themselves. The remedy is to separate the threads and pull tight again.
Sometimes the gimp slides down to the side that I pull with, then it won't let me tighten any more. Any gaps left by that are difficult to undo. The remedy is to keep the gimp down tight to the non-pull side with a thumb and pull all the thread through until it is tight. If it is not pulled tight enough, then stretched, there will be a gap.My only objection to Power Pro is the lack of color choices, though most dark pearls look fine on the moss green.
While I am at it, I don't like Dandyline as much as PowerPro because it is slippery and tangles easily without a light coat of wax. It does come in a silvery black as well as white and that is helpful. Knotting with four threads is especially hard with d-line.