Test results, which do I believe?

My water went cloudy yesterday and I discovered that my frog mineral system was out of chlorine in the cartridge (it uses trichlor tabs from what I can tell). It lasted much less time they said it would when I bought it (go figure). I didn't have a test kit yet so i took in a water sample to the pool store and these were the numbers that they gave me.

TC: 0
FC: 0
pH: 7.6
TA: 139
CYA: 65

I am planning on switching to BBB, but not ready to pull the trigger just yet, so I left the pool store with a new cartridge for my frog mineral system and a couple bags of shock to get some FC back in the water ASAP.

Throughout the day my water has cleared up significantly, but I was curious about my numbers so I went out and bought a test kit from Walmart (the HTH 6 -way kit). I tested pH, FC and CYA and this is what I got.

pH: 7.6 - same as my pool store
FC: > 5 - this is as high as the test kit goes. I will test again in the AM to see if it's dropped.
CYA: < 30 - I filled the test tube up to the top and I could still see the black dot quite well. I guess I don't know, using this test what my CYA is, but this test is telling me it's well below 30.

Which CYA value would you believe? Pool store or mine? Should I retest CYA with my kit again just to be sure? If it's as low as my test shows, I think I could probably use some additional stabilizer to bring it up a bit.

TIA

Did your pool store use the 'disappearing black dot' test to test for CYA? If I were you, I'd trust my own CYA results. We typically suggest a CYA reading of 40-50ppm for most pools.

You can force your test kit to read higher than 5 with a dilution method described here: Testing Without a Good Kit


We don't advise people to use the Frog Mineral system. Those mineral systems add metals to the water -- specifically copper. Contrary to popular belief, it isn't chlorine that stains pool surfaces, fingernails and blonde hair green. It is copper! You do NOT want copper in your pool. Do yourself a favor and ditch the cartridge.

What are the ingredients of the bags of shock you bought?

Go ahead and order a good kit -- Taylor K2006. It will make your pool maintenance much easier.

No, they used a test strip with a bunch of dots on it and fed it into a small machine (probably a color analyzer). I used the black dot test with the kit I got from WalMart which tells me I need to add some stabilizer; that should help me get some more life out of my chlorine.

Once the trichlor tablets run out of the current frog cartridge, that thing is gone. Copper aside, I hate not knowing what is in my pool. I don't like the fact that it's "supposed to" keep FC between 0 and .5. That just doesn't sound right to me; and borderline unsanitary.

I have the Taylor K2006 kit on the way; should be here on Friday. I'll be going to liquid chlorine as soon as I get it re-piped. Thanks again for all your help, and for this wonderful forum/website. There's a lot of great information here!