Regarding the double knot question, does that mean to tighten onset tzitzis is or Tallis knot at the top would be mutar since it never really gets tight and one sees it comes out all the time?
Answer:
If the knot will become loose of its own accord – to a degree that it cannot be seen as a knot – without you taking any action, it seems that you can be lenient.
However, if the knot is made truly tight, it stands to reason that it won’t become undone by itself, and it won’t be permitted.
Best wishes.
