Problem with cloudy in-ground pool. Brown residue on liner.

It would really help if you had the good Taylor K-2006 kit because your readings would be much more reliable and your chlorine test could read higher than 5ppm. Plus, it would help us to know your CC reading.

An OTO kit can only read chlorine levels to 5ppm so your chlorine may be higher than 5. 5 is not shock level for any pool. You can force your kit to read higher by using a dilution method described here: Testing Without a Good Kit

What kind of liquid shock are you using. (What percentage sodium hypochlorite is it?)

Purchased the Taylor Kit online from Amazon as you suggested. Should arrive on Monday.
I am using 6% Bleach and added 2 gallons yesterday.
I just added a CYA tab to my pump filter. Was that a good idea?

Otherwise I am brushing and vacuuming and backwashing.

Pump is staying on.

It was fine to put a tab in the skimmer since your CYA is low. Just make sure the pump doesn't go off for more than 8 hours. Also, do not add other ingredients on top of that tab.

Good decision to get the kit.