Different results from pool stores-please help

[hancop]

I live in the Toronto Ontario area and went to two seperate pool stores for water testing last night and reiceived very different results.

Pool store one uses strips and a scanner to scan the strips colour, which I find highly suspect and am tempted to ignore the results, even though they tell me since the scanner checks the colours that it is very accurate.
Pool store two uses the standard drop tests with colour changes.

At pool store one and two my chlorine level and PH were identifed as being the same, but CYA at pool store 1 was 10, and pool store 2 was over 100. I have the taylor 2006k test kit and my test shows CYA of 30. At pool store one my calcium level was 260, and at pool store two it was 110. My taylor 2006k test kit shows it at 110.

The main reason I went to the pool stores to get my water tested was that I wanted to double check my results and purchase calcium chloride to bring my calcium level up to about 200 -230 ppm. I have a vinyl pool with a heater, but the reason I want the correct calcium level is that I have a concrete surrounding the pool and don't want corrosive water to be pitting my concrete.

At this point based on the results I am not sure if I should add calcium or not, as pool store one tried to tell me that our water out of the tap is 250 ppm which is what I used to fill the pool with. Yet my testing and pool store 2shows my calcium level to be low.

At this point I am tempted to believe my tests and pool store two and add about 10kg of calcium chloride to bring my calcium level up to around 210 ppm, assuming pool store 2 and my results are correct.

What would others do in my situation ?

Thanks

[Spensar]

I'm in Ottawa and hav had a similar experience with the CYA results, but with the same store. I've had them tell me it was zero after I added CYA and wanted to check what my level is, and this year I changed liners and brought to new city water for testing and they said the CYA was 30! I have a Taylor 2005 now and it showed zippo CYA.

I would do your own test, even twice to be sure, and take the pool store with a grain of salt.

On the calcium, can you have too much for a heater and end up with a build-up. I really don't know and hope someone here may help.

[aylad]

What would others do in my situation ?

Thanks

Forget the pool stores, and believe your own testing.

Janet

[kwong]

Ditto on doing the tests yourself!

I also have the Taylor K-2006 and believe as long as you follow the directions properly you should be fine ..
i.e.
1) keep titrants vertical when adding
2) obtain water sample 18" from top (and not from return area)
3) use sample immediately .. don't sample from large quantity from large bowl that you have obtained water sample (in order to prevent multiple arm dipping .. some people don't like that apparently)
4) try to maintain same/similar drop sizes when adding titrants
5) try not to expose your chemicals to direct sunlight (store in cool/dry place)
6) cya testing is very subjective .. see http://www.poolforum.com/pf2/showthread.php?t=7761
7) ensure that water sample is fairly accurate ... when looking at comparator tube .. ensure mid-portion of waterline matches 44ml/25ml mark (and not the sides)

8) you may want to log your progression .. you can see history and what chems you added when and what effects have occurred in the past

hope this helps .. i too am from Toronto region .. not sure where you get your chem testing from .. but when i was acquiring my kit .. the store had been testing someone elses with titrant method ... poolmaster .. off 401 .. south Leslie St. ... they also stock titrants and other smaller kits (as well as k-2005)

[giroup01]

The calcium test takes a while to complete if performed properly. Make sure that each titrant drop is completely 'dissolved' (wish I had a better word for it) before adding another drop, make sure the reaction completes for each drop you add. The color change is not as instantaneous or as sharp and vibrant as the TA test and so take your time.

The LPS here just adds drops one by one continuously and they stop counting when the sample changes color. By slowing down they would observe that the color change happens earlier if they just let the drops mix thouroughly before adding the next one. Conclusion they're off I'd say by 4 to 6, maybe 8 drops.