What are small red worms that constantly swim and make figure eights they are approximately 14 of an inch in length and seem to have taken over my pool How to get rid of them?

I had the same question. After a little research, I'm pretty sure they are "bloodworms", which sound horrible but are actually harmless. They are midge larvae (midge are small flies).

See also this web page:

http://www.naturegrid.org.uk/biodiversity/invert/midges.html