discolored pipe in generator system

[poolbee]

As in another post, my chlorine has been up for a while and it doesn't want to go down, but it seems the consensus is that's OK. I let my pH get to 7.8 before adding acid to get it to about 7.4. I haven't added acid in over 2 weeks though. It seems steady at about 7.6.
Before the CL went up, it was usually 3-4.I was looking at that valve today and I'd have to change my description of it as looking dirty inside. It looks like the water is cloudy. It is still translucent, but dirty looking. I did have major dirty, dusty work done in the yard(Unilock patio with literally tons of crusher run and sand, and yards of dirt spread around the landscape). The pool was full of dirt on a daily basis for about 2 weeks and I ran my Dolphin cleaner daily to try and keep the dirt out of the filter. Could this have settled in the valve?

I have only had the unit since the end of May this year. What does the check valve do? Is there a way to clean it?