First of all, thanks to everyone who has responded. To answer your questions, my pool holds 35,000 gallons of water. I am using a brand of chemicals called Bioguard, which is purchased at the pool store. Prior to draining my pool of 1/3 of the water, the readings were as follows: CYA: not tested; Total Chlorine 0; free chlorine 0; PH 7.7; alkalinity 158; calcium hardness 129; iron and copper - not tested.

After draining the pool 1/3 and refilling; I then added another 6 lbs of shock and moved the chlorinator dial from 2 1/2 setting on the dial to a 3 setting.

Water was tested today, results are: CYA - not tested; Total chlorine - 0; free chlorine - 0; ph - 7.2; alkanlinity - 95; calcium hardness 100; they have advised to add chemicals (since i drained water) to raise alkanlinity; add chemicals to raise ph; add chemicals to raise calcium, SHOCK AGAIN and they advised me to move the chlorinator dial up to 4. I'll retest in 24 hours at the pool store.

I used a home testing kit (not the strips) yesterday and had chlorine readings; but the pool store had no chlorine readings. they said the test kit chemicals i was used was probably expired and i was getting false readings. i looked at the chemicals and they had expired.

Hope this will help you resolve my problem. thanks again