Today's numbers-

FC = ~5 as measured with OTO.
pH - 7.2-7.4

I went swimming today. The water has a very nice color to it, all the other chemistry is in good shape...but the water is just CLOUDY.

After donning a mask and looking around underwater I am thoroughly convinced that my sand filter has failed in some way. Either the sand has been backwashed out or the valve is leaking by somewhere. There is just a lot of particles in the water. Stuff that is visible to the eye, not just real small stuff. The pump has been running 24/7 and on low since last week. I'm gonna have to take the top off again and see what the sand level is.

Going by the "grocery store" philosphy what kind of sand do I need? I usually buy the pool store stuff but I'm pretty sure that I can get some from the lumberyard that will do the trick.

By the way I used the DE trick and didn't see any results. I also did not notice any DE blowing back into the pool, so I'm at a loss on what to do next. I'm ready to go back to full on DE, I consider the sand filter experiment failed. Unless I can resolve the "problem" of sand being backwashed out.