Water cloudy, have test results

[BigDave]

You don't need calcium in your vinyl lined pool. Given your two readings, 211 and 50, if either is correct, calcium shouldn't be causing the cloudiness.
Sounds like your Brother In Law did well.
I'm pretty sure that "chlorine lock" is a pool store myth, sounds like you may suspect that as well. However, if you have algae (and you did) and it's not all dead, you could be just holding it at bay with all the chlorine you're putting in without making real headway.
As you supect, you do need more chlorine. According to Ben's Best Guess Chart, your regular operating Free Chlorine level should be between 3 and 6 for CYA of 40 and 15 for shock level. If this were my pool, I'd raise the FC to 15 and keep it there until the pool loses less than 1ppm FC overnight (sundown to dawn) with nearly 0 Combined Chlorine. It willl take about 3-1/2 gallons of 6% bleach to move your FC from 2 to 15, and you'll need more to keep it there so stock up.
You will need the K-2006 kit to measure these values. Have you ordered it yet? You may have noticed the the pool store tests show a wide variance, you really do need to be able to make accurate measurements yourself.