Calcium Hardness went down after adding Calcium Hardness Increaser

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R

Randomizer

0
May 25, 2011
11
Western New Jersey
pool is 24,000 gal in ground gunnite pool.
on 5/23, shortly after opening, I tested FCL, TCL, PH, Alk & CH using chemical test kit. Alk was 68 AND CH WAS 77. I added about 5.5lbs of baking soda, which was all I had on hand, to bring Alk up and ordered more along with calcium hardness increaser. Baking soda arrived and I added another 4lbs on 5/26. On 5/27 I added 15lbs of calcium hardness increaser.
Tested again on 5/28: Alk was at 96 ... great. But CH was now at 18. What??? How could that happen? Tested again a few hours later and CH was 39, still below the original starting point fo 77. I added approx 3 lbs of calcium hardness increaser (did not want to add too much in case something else was wrong). Tested again today it is is 43.
 
My gut instinct is that you have an electronic tester and it's out of calibration.

Second thought is that the pH is way high and all that Calcium is now stuck to the walls in the form of scale.

Third thought is that you have a slow leak and an autofill and the replacement water is high in TA but low in CH.
 
Following up on Richard's thought, how are you testing? None of the test kits we know to very accurate will give a CH level,like 77 or 39.

So, as Richard suggests you are using. ColorQ or are having your water tested at a pool,store who uses a spin lab. In either case do not confuse the specificity of the result with accuracy. We have seen reports here of ColorQ results and I have personally had water tested on spin labs that were way off. The reports look,nice, it's just that the results they give can not be counted on all the time. When are they right? Who knows.

We rely on drop based testing using Taylor reagents. The results are accurate and repeatable. Anything else andIt's like you are guessing. .
 
Nope, the ColorQ is not drop based testing. Members he who have attempted to use a ColorQ have abandoned its use because it has anomalies in testing, like CH going down after adding CH.

To be honest you need a TF-100. If you can count drops you can accurately determine all the parameters of your pool water. TF-100 @ TFTestkits.net

As I said, don't confuse the specificity of the results the ColorQ gives with accuracy. We had one member who tested one sample of water three times and got three different sets of results.
 
Randomizer said:
I'm sorry to hear this. One of the reasons I purchased the ColorQ was that specificity and, in particular, that I would not have to do color comparisons.
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The only color comparisons with our recomended kits is the pH test. All other tests are either color elimination, pink water to clear or a color shift, like red turning green.

As you have proven, the ColorQ is giving results that can't be trusted. If your pool has X amount of CH and you add more CH the next set of results can't be lower unless you replaced water.
 
There are few tests in the TF100 that require any color comparison. They are mostly titration tests, where you add and count drops until there is a dramatic color change, that is very obvious. The pH test is about the only one that requires comparing the color. For those who can't read it, some use pH meters. Not as accurate and require regular calibration, but that's the cost of color blindness.
 
Randomizer said:
I'm sorry to hear this. One of the reasons I purchased the ColorQ was that specificity and, in particular, that I would not have to do color comparisons.
Click to expand...
Do not confuse specificity with accuracy. There are few if any situations where knowing things like FC or pH to the hundredths or TA/CH/CYA to the single digit is going to be useful.
 
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