Help me please!

[Corrinna]

Ok here I am again. Went to two pool stores yesterday with samples of my water. Incredible......both differed from one another and also from my own tests. I am SOOO confused. I understand most of what I read here but if you don't know which test results to go by you don't really have a starting point. The first pool place analizes water with computer based system although I did see her manually enter the CYA value so she must of tested that manually. The second place analizes all of their readings manually with drops. Here are the readings:
CYA 100.............40
TC 1.7................3.0
FC 0.5................0.4
PH 7.4................7.5
TA 180...............160
Adj TA 150..........not done
(first column first store, second column second store)



Thanks again for any comments.
Corrinna

[Corrinna]

Okay here I am again. For the past 2 days I've been monitoring and shocking my pool to get it clear. As posted in my previous post one pool store said I had a CYA of 100 while the other store said my CYA was 40 (both water samples were taken at the same time and were tested within 20 minutes of each other). I decided to use the higher reading in order to determine how much bleach to add to shock. I shocked beginning on Wednesday night, Chl level was still at 25ppm the following morning and did not show a drop until mid to late afternoon, added enough to raise level to 25ppm again last night, reading this morning and at 2pm today remained at 25ppm. Reading now is approx 16ppm. Will add more to raise to 25ppm again and hopefully water will continue to clear....it does look clearer-I think! Will have my water tested at the pool store tomorrow to get a new CYA reading. It seems my chlorine level isn't dropping very quickly since it doesn't drop over night....it's taking approx 18 to 20 hrs to show a drop. Is that significant? Do I keep shocking until water becomes crystal clear?

[CarlD]

20 hours to drop is good.

Now, are you running your filter 24/7, vacuuming to waste everyday, and brushing the pool everyday? You should be.

If the CYA of 100 is right, then the shock level of 25 is right. If the CYA level is 40, you may well bleach your liner. This is why it's best to test yourself and rely on your tests. Ben's kit, the Taylor 2006 or the Leslies FAS-DPD Chlorine Service Test kit are the best ways to be sure. They are all basically equivalent, but I won't go into why I think Ben's kit is the best--all 3 are better than everything else out there. But some WalMarts have a 5-way drop test kit that uses OTO to measure TC up to 5, measures pH, T/A, CYA and hardess, all for less than 15 smackeroos--a bargain.