Calcium Hardness Doesn't Match

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Jan 5, 2012
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I have the TF100 test kit and I've run the CH test twice and both times got 540. I don't know if I'm doing something wrong or not.

The first time I used the original chemicals from the kit I got last year. I just received some refills so I used those for the second test.

I took the water to Leslie's because this was so high and I'm not seeing any calcium residue. They're getting a CH of 340 which is more believeable. All their other tests were in line with what I've been getting.

Any ideas why the TF100 is reading so high?

Thanks,
Mike
 
As long as you are following the test directions, I would believe the TF-100 results over the pool store results any day. Especially since you were able to replicate the results again. Also, just because you haven't seen calcium on surfaces doesn't mean it is (or isn't) high. It all depends upon what your CSI is and that can be managed effectively with CH levels much, much higher than 500 to 600. We have members here whose CH is around 1000 or more and yet the can still keep their calcium in solution and off pool surfaces.

Have you checked the CH your fill water source?
 
CH is a difficult test. Did you read the extended test directions thread? There are recommendations in there that may help.


- Sent using Tapatalk
 
If the drops of titrating reagent are not well-formed, then wipe the dropper tip with a damp cloth. Drops that are too small will result in a higher reading than the actual value. Usually this is more of a problem with the TA test, but static electricity could build up on bottles for other tests.
 
Thanks for the quick replies. I really appreciate it.

I tested the incoming fill water and it has a CH of 80.

The pool has only been up and running since the beginning of the year. The CH started at 160 in January and has been slowly climbing until the past two months.

Feb - 220
Mar - 250
Apr - 280
May - 290
Jun - 330
Jul - 380
Aug - 440
Sep - 540

The pool builder gave me 50 pack tube of Pentair test strips and I just use those on occasions to confirm the TF100 results to make sure I'm not screwing things up. The test strips show a hardness between the 250 and 450 colors (closer to the 250). This would be in line with the Leslie's readings.

The R-0011L doesn't really drip that uniform because it's fairly viscus but the hole and tip are clear. I didn't get that in the refill so if that's bad, I could see where it could be affecting the results. Perhaps I should get a replacement for the R-0011L? Is it suppose to be a little thick?

Thanks,
Mike
 
Any chance you have recently been using any cal-hypo (shock)? That could account for the rapid CH rise. The test strips are really not going to do much good ... large ranges and subject to color interpretation.
 
scoreboard said:
The pool builder gave me 50 pack tube of Pentair test strips and I just use those on occasions to confirm the TF100 results to make sure I'm not screwing things up. The test strips show a hardness between the 250 and 450 colors (closer to the 250). This would be in line with the Leslie's readings.

The R-0011L doesn't really drip that uniform because it's fairly viscus but the hole and tip are clear. I didn't get that in the refill so if that's bad, I could see where it could be affecting the results. Perhaps I should get a replacement for the R-0011L? Is it suppose to be a little thick?
Click to expand...

Have you read this post in the extended test kit directions thread? extended-test-kit-directions-t25081.html#p206396

It details that if the R-0011L stains the bottle - it isn't any good - but it doesn't speak to viscosity.

Read all of the notes - there are some interesting options to consider depending on how this has been working out for you.
 
Feb - 220
Mar - 250
Apr - 280
May - 290
Jun - 330
Jul - 380
Aug - 440
Sep - 540
Click to expand...
Those results would make the TF-100 results far more logical than the 340 you got from Leslies. It shows a steady progression.....CH doesn't go down, it typically increases although that's a pretty fast rate......I would still bet your CH is 540 instead of 340.
 

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scoreboard said:
I have the TF100 test kit and I've run the CH test twice and both times got 540. I don't know if I'm doing something wrong or not.

The first time I used the original chemicals from the kit I got last year. I just received some refills so I used those for the second test.

I took the water to Leslie's because this was so high and I'm not seeing any calcium residue. They're getting a CH of 340 which is more believeable. All their other tests were in line with what I've been getting.
Click to expand...


scoreboard said:
I tested the incoming fill water and it has a CH of 80.

The pool has only been up and running since the beginning of the year. The CH started at 160 in January and has been slowly climbing until the past two months.

Feb - 220
Mar - 250
Apr - 280
May - 290
Jun - 330
Jul - 380
Aug - 440
Sep - 540
Click to expand...

When I first read this thread I assumed you had not tested your CH except for two times and those were spread out over time. Now I understand based on these quoted results that you have been seeing it go up - and you verified the 540 result twice most recently - correct?

You had Leslie's check the most recent sample - did you have them check any previous one's? Have you asked them to test your fill water to see what result they get from it?
 
You might read this link that mainly describes what is going on for a fading endpoint during the CH test but does have some interesting info about the test, consistently-wrong-on-ch-test-t20339.html. One of the problems that people have with the CH test is that they don't swirl the water enough. Having a speedstir really helps this test out, especially when the CH level is fairly high.

I suggest doing a test with only 10ml of water that is described in the extended directions in UWV's post above. It will not be quite as accurate as using 25ml of water, but there will be less swirling during the test.

If you still get 540 using these methods trust your testing. You have probably been losing a lot more water the last couple of months due to evaporation which is driving up the CH level.
 
scoreboard said:
The R-0011L doesn't really drip that uniform because it's fairly viscus but the hole and tip are clear. I didn't get that in the refill so if that's bad, I could see where it could be affecting the results. Perhaps I should get a replacement for the R-0011L? Is it suppose to be a little thick?
Click to expand...
The drop formation I was referring to was for the titrating hardness reagent R-0012. The R-0011L is somewhat viscous/thick -- that's normal. The color should be dark so your sample should be a clear pink/red, not a light pink.
 
The pool is just a year old this month.

I talked with Duraleigh last night and he was a wealth of information. Basically we calculated it out.

I was told by my pool builder that here in the summer months the pool could lose as much as an inch of water per day to evaporation. Based on our calculations that would be somewhere in the ballpark of 30% of the pool water per month or 1% per day.

The reason the numbers didn't jump up in the middle of summer is because we had unusually high humidity for 2 months which slowed the evaporation.

In talking with the pool builder, he said that most people in the area dump their pool every three years and that he's a little surprised by the large increase in just a year. He recommended getting the water tested at one or two different shops just to make sure the reading were in order.

Duraleigh is certain the R-0011L is good and I agree with him. Just for final peace of mind, I'm going to take a sample of both the pool water and the fill water to a couple of different pool stores to see what they come up with. I'll keep you posted.
 
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