WOW ... I was really slow typing this one.
Sorry I missed the pool size somewhere.
You are not using the term "shock" how we usually do, so I am a little confused.
Can you be more specific about the chemicals?
How large a jug of bleach is $5 (is it 6%)?
What is the 5lbs for $14, dichlor or cal-hypo? If cal-hypo what strength?
The problem that has been show on the forums repeatedly, is that the pool store tests are notoriously inaccurate and inconsistent. Sometimes showing huge changes day-to-day that are not chemically possible. SO, you end up buying products chasing numbers that are not correct. That is why we say it is cheaper to buy the test kit and KNOW the levels are accurate and repeatable ... then you know exactly what your pool needs and not what the store is trying to sell you.