How much chlorine is needed to add to a pool?

I have not been able to get my pool to hold any chlorine since opening it two weeks ago. Today I had my water tested and was told I had a high demand and needed to add 21 pounds of shock to rectify the problem. The pool store got upset with me for purchasing...

Just a quick question.. Do all pools need added chlorine. I once had a salt water pool which I added chlorine to when needed but now my in-laws have one and are saying that they don't 'ever' need to 'manually' add chlorine because it has a chlorinator...

All the chemicals in my 20x 40 AB pool is correct except chlorine and stabilizer. Both are zero. We have tested for everything from phosphate to metals. All came back fine and since still have swamp green pool, we treated for both of those twice now...

in order to save money these days i have decided to clean my own pool the peoblem is i dont know how. i added chlorine and started brushing my pool and it got really foggy. i replaced 2 filters thinking they had holes. i brushed and vacuumed the pool...

if 15 units of chlorine is the amount nedded for 2500L of water, how much chlorine is needed for 3750Lof water?

I have a large family pool 120" x 72" x 22" with a 264 gallon capacity, I am wondering what chlorine product I can put in it to add some cleanliness and safety for my 3 year old in the water. It is a waste of water to keep emptying it.

we just bought a pool and i am needing to know if chlorine must be added and should it be shocked

I am a pool operator that in VA that had a small "drowning" problem in our pool.

our pool got green on vacation.it's an intex.cleaning filter 2-3x a day.like i said, ph is good,chlorene is a little high.adding algaecide every day.it's not counterproductive is it? been trying to clean up for 2 weeks now.sweeping 2-3 x a week.shocking...