I went to those links @REI-JohnJ  posted and was really impressed!  And I'm so happy I learned some things today!

I would suggest, if I may, that while you're at it, you take some time to inspect the floor of the tent for tiny 'micro holes'.  I usually hold the floor up to a good light and can spot the holes with the light shining through. 

As a 'hasty expedient' I have used tiny squares of my medical tape to patch tiny holes, and have been pleasantly surprised that these patches last for years.

Further, you can make your own silicon based sealant (and save big bucks) by purchasing from a hardware store a tube of clear silicon and some mineral spirits, mix in equal parts, and brush on.

Here's a link to a video on doing that. https://www.tarptent.com/seam-sealing/

Good luck!

REI Member Since 1979 YouTube.com/philreedshikes