Confused on what is settling at the bottom of my pool

[jdubh]

I have been battling and issue with where I have the dark black stuff that settles to the bottom of my pool and when I brush it, it clouds up.

Around I month ago I was having the same issue, and I slammed my pool which worked. Since then, I have maintained my ph and cl levels to the recommended levels on this site.
A few weeks ago, it came back. I slammed again but it didn't seem to help. (I followed the SLAM guide) In the last 2 weeks I have been brushing and vacuuming the pool almost every day and also changing the filter daily. One day I also vacuumed to waste and filled the water back up to the normal level. (I am on city water but it's not the best) The next day it was even worse. So, I figured it must be iron. I then dumped a half of jug of iron myte in and the next day it looked great with minimal black stuff on the bottom. The next day It went back to the way it was.
I am hoping to add pictures but the last time I tried it didn't work.

I do clean my filters and brush with hose water. Could that be causing my issue.
Is my vacuum set up not actually collecting the algae/rust or whatever it is?

 

[ajw22]

You have iron in your pool water. You will not fix the problem until your drain and refill with iron free water or try to filter out the iron using polyfill.

Read Iron Fill Water Filter - Further Reading