Calcium Hardness Test. Very different results.

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Pat_

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Sep 19, 2018
13
Brisbane
Hi,

I'm hoping someone like chemgeek can help.

I had been using a Taylor Technologies based test kit (from Clear Choice Labs here in Aus) which for Calcium Hardness uses R-0010, R-0011L & R-0012 reagents. I have confirmed the validity of these results using the Taylor Calcium Hardness 200ppm check standard. For my pool specifically, I generally test around the 300ppm using this kit.

Now this is where it gets confusing, and I can't for the life of me figure out what is happening. I recently purchased a Palintest Pooltest 6 photometer which also performs a calcium hardness test. Following the instructions exactly, I get a result of 135ppm. Vastly different to the 300ppm I get from the Taylor titration kit.

Given the difference, I sent my Palintest back to the manufacturer to confirm calibration, and it tested well within calibration standards. In fact it tested exactly to the required standard.

From what I understand the Taylor Calcium Hardness test is Calcium Hardness only, and not total hardness. Is that correct? I'm not sure what's going on, but the difference is significant and either means my CH is exactly where I want it to be (300ppm) or I need to add 8kg's of hardness increaser to my pool. I definetly don't want to add that unless I'm 100% I need too!

Current Test Results:
FC 1.6
CC 1.6
PH 7.6
CYA 15 (due to ORP probe. CYA interferes with this)
TA 80
CH either 135 or 300?
 
Hi Pat, I have been having issues with my CCL CH test. I always thought my ch was 225 until one day I started getting strange inconsistent results. One night I tested at least 7 or 8 times with the same water sample. I got readings from 300 - 800 [emoji15] I checked my standards and it was way off. It measured 300 rather than 200. I ordered a whole new set and the standard is spot on. Unfortunately my ch is reading just over 500 with the new test and I believe this to be correct. I have a feeling that my old reagents were faulty all along. Thank goodness I didn’t add any calcium based on the old test results. I have sent Brett from CCL a message on here and also left a voice message but haven’t heard back. That was a couple of weeks ago now. What is your batch #? I still have my old ch test that I kept in case they wanted to test them. Mind we’re purchased probably April/May this year as part of the complete salt water test kit.
 
Hi Riley,

Thanks for the reply and good to see someone else from Bris. I had purchased the Complete Salt Water kit back in Jan this year, so its not inconceivable they're from the same batch. My check standard tests at 200PPM though, so it appears to be giving accurate results. I will try and make up my own 200PPM solution and see if I have any success testing that.
 
I'll check my batch numbers when I get home.

On another note, I also have the Astral EQ35 with PH & ORP probes. My PH probes has been rock solid since installation, however my ORP probe has been nothing but trouble. ORP will drop / rise 200 points overnight, then it will spend the next day or two at 100% output until it hits the set point again. Then a few days later it will realise it's way past the set point and sit at 0% for the next week. Very odd behavior.
 
Pat_ said:
I'll check my batch numbers when I get home.

On another note, I also have the Astral EQ35 with PH & ORP probes. My PH probes has been rock solid since installation, however my ORP probe has been nothing but trouble. ORP will drop / rise 200 points overnight, then it will spend the next day or two at 100% output until it hits the set point again. Then a few days later it will realise it's way past the set point and sit at 0% for the next week. Very odd behavior.
Click to expand...

I also have the eq35 but with only the ph probe. The orp probes don’t have a good name on here I’ve noticed. In case you ever want to ditch it you could just run the swg without it. Now mine is dialed in I never need to touch it. I do expect to have to increase by one notch or so during summer. My FC happily sits at 6-7 (cya 70-80) on setting 4 with two cycles of four hours a day. Ph probe and auto dosing takes care of the ph. I don’t really have to do anything other than test. Just added my first small amount of cya since start up in May. It really is a trouble free pool without the orp (well the water is - don’t ask me about the pool leak, that is a different story and far from trouble free [emoji31]).
 
riley00dog said:
Lot # from my old faulty test.

Triating reagent E2066
Buffer B4039

I think the detection reagent was fine as it’s the same lot number as my new kit. The triating reagent and buffer have different lot numbers though, so I suspect it’s one or both of these.
Click to expand...


Liz,

My batch from my kit has the same lot numbers - E2066 & B4039 yet my CH testing has been extremely consistent (as we proved the other day via PM) - Testing my pool water as well as my supplied standard has shown no irregularities.

Suspect that there maybe something else going on?



Pat_ said:
On another note, I also have the Astral EQ35 with PH & ORP probes. My PH probes has been rock solid since installation, however my ORP probe has been nothing but trouble. ORP will drop / rise 200 points overnight, then it will spend the next day or two at 100% output until it hits the set point again. Then a few days later it will realise it's way past the set point and sit at 0% for the next week. Very odd behavior.
Click to expand...

Liz and I will both concur that the PH probe (when calibrated correctly) works very well and tracks our test kit results without drama.

Too many variables that can affect the ORP probe - CYA, UV exposure of pool (burns off free chlorine) etc etc.

Best bet is do what Liz and I do - Don't use the ORP probe and don't use the AI function of the chlorinator.

Bump up your CYA level as per TFP's recommended levels and manually set the chlorine output on the chlorinator - Works way better and will also save you money on not having to run the pump for endless hours on end to try and satisfy the ORP probe's inconsistent readings.
 
Costas > DownUnder said:
,

My batch from my kit has the same lot numbers - E2066 & B4039 yet my CH testing has been extremely consistent (as we proved the other day via PM) - Testing my pool water as well as my supplied standard has shown no irregularities.

Suspect that there maybe something else going on?
Click to expand...

Hmm. Yes, that’s strange. Something going on with it but obviously not a faulty lot as yours are fine. I wonder what it is. My testing has been consistent since I received my new kit.
 
Pat_ said:
Hi,

I'm hoping someone like chemgeek can help.

I had been using a Taylor Technologies based test kit (from Clear Choice Labs here in Aus) which for Calcium Hardness uses R-0010, R-0011L & R-0012 reagents. I have confirmed the validity of these results using the Taylor Calcium Hardness 200ppm check standard. For my pool specifically, I generally test around the 300ppm using this kit.

Now this is where it gets confusing, and I can't for the life of me figure out what is happening. I recently purchased a Palintest Pooltest 6 photometer which also performs a calcium hardness test. Following the instructions exactly, I get a result of 135ppm. Vastly different to the 300ppm I get from the Taylor titration kit.

Given the difference, I sent my Palintest back to the manufacturer to confirm calibration, and it tested well within calibration standards. In fact it tested exactly to the required standard.

From what I understand the Taylor Calcium Hardness test is Calcium Hardness only, and not total hardness. Is that correct? I'm not sure what's going on, but the difference is significant and either means my CH is exactly where I want it to be (300ppm) or I need to add 8kg's of hardness increaser to my pool. I definetly don't want to add that unless I'm 100% I need too!

Current Test Results:
FC 1.6
CC 1.6
PH 7.6
CYA 15 (due to ORP probe. CYA interferes with this)
TA 80
CH either 135 or 300?
Click to expand...
Probably both! From your Palintest manual:
The expression of hardness results sometimes causes confusion. It is normal practice to express the results of hardness tests as mg/l CaCO3 (calcium carbonate). This is merely a convention to allow the comparison of different results and does not necessarily indicate that the hardness is present in the water in this form.

Results may also be expressed as mg/l Ca. To convert mg/l CaCO3 to mg/l Ca multiply by 0.4.
Click to expand...

The Taylor kit results are ppm CaCO3. The Palintest can be either ppm CaCO3 (Phot 12 option) or ppm Ca (Phot 60 option). Multiply the 300 ppm CaCO3 by 0.4 and you get 120 ppm Ca, which is pretty spot on to your Palintest results. So check your testing settings and retest. You'll always want ppm CaCO3 since that's what everyone else uses.

You could also try the 200 ppm standard in the Palintest to see what the result is.
 
You want to make sure you use the photometer setting that’s expresses the hardness in units of calcium carbonate (CaCO3) for a very important reason - all of the saturation index calculations (whether one uses LSI or CSI) assumes the CH value has units of CaCO3 and then internally calculates the calcium ion (Ca2+) concentration. If you use a value for calcium ion, you will get a false-low CSI value in PoolMath.
 

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Thanks for the suggestions so far! I have the Pooltest 6 model which only displays calcium hardness as CaCO3 so that can't be the issue. If you want to convert that back to Ca then you must manually do the conversion.

jseyfert3 - I did try the 200ppm standard but I messed up, I didn't zero the palintest with the standard first. So any results I got from that are incorrect. I will first try and make my own standard solution, if that fails I'll just go ahead and order another standard from CCL.

- - - Updated - - -

riley00dog said:
Lot # from my old faulty test.

Triating reagent E2066
Buffer B4039

I think the detection reagent was fine as it’s the same lot number as my new kit. The triating reagent and buffer have different lot numbers though, so I suspect it’s one or both of these.
Click to expand...

Lot Numbers are as follows:

Hardness Buffer - B4039
Detection Reagent - C4099
Titrating Reagent - E2066
 
Hey everyone sorry I'm late getting back to you, I've been not well for a couple weeks but that's going away now.

We make a large batch of reagent, but it's not all bottled on the same day due to volumes. So the same batch number might be bottled a month apart for example - we've got some new equipment and we'll move to a bottled date sticker. This will also help with knowing how old your reagent is.

I think Liz has some of the newer bottled reagent, and maybe something has happened between bottlings. If the large reagent lots aren't sufficiently mixed before bottling it could in theory change the concentrations, which (again in theory) could change the longevity of the reagent and the way it responds. We have more tests to do in that space. Sorry it has been giving weird results, I know pools are hard enough to manage sometimes without the tests causing you to second guess yourself.

What I've noticed over the past year or two is that the CH standard can age quickly, so after some time it takes extra drop or more to get the colour change, and it looks like the CH levels have risen. Also with the CH Buffer as the formulation ages it can be less effective as a buffer, causing these issues as well. Once the buffer goes, the reaction that occurs is anyones guess and so it'll literally be all over the shop. From reading this thread I suspect the CH buffer is failing for some people and the standard is maybe aging earlier than it should. If you're unlucky and get both issues, you're going to see really weird results. It shouldn't have happened this quickly though, so we'll look into that.

Definitely for those of you who ordered and received new reagents this week you should find the issue is fixed. I hope so! But if it isn't please let me know or post it here and we'll have a look and fix it for you. Last year CYA testing was the issue, it looks like old Calcium Hardness got jealous and wants some attention this time :eek:
 
Thanks for replying Brett and for replying to my pm. That certainly explains a lot and I think likely the buffer was my issue. Happy with my new ch kit and it appears to be working as it should. Yes, the results were varying wildly with the old solutions. Happy to send you my old stuff if it’s of any use. Date of manufacture will be a great addition. I hope you’re feeling better soon [emoji4]
 
I have done some further testing after making my own backyard brew 200ppm CH standard from Calcium Chloride and demineralised water. There's a bit of wiggle room here with the accuracy, but I did the best I could with kitchen utensils.

Results as follows:
Palintest = 178ppm CCL = 250ppm

I did a second test using my pool water again:
Palintest = 130ppm CCL = 350ppm
 
That second test has a huge discrepancy. Have you ordered a new CCL ch test? Mine has been consistent but concerned that since start up my pool’s was much higher than I thought if this new test is correct. I was actually testing to determine how much calcium to add as it was a little low lol. Glad I didn’t add any more. I’ve plugged a few retrospective numbers into pool maths and it seems that my csi was never out of range and I have no scaling that I can feel. This other test test you are using where did you get it?

Btw Amazon no longer ship anything non digital to Australia. I went to buy a back up speed stir and no go. Even the hairnets. Nope. Apparently as of July 1. Not happy as the speed stir isn’t on the AU Amazon. Nothing is; it’s rubbish.
 
Given the bigger difference on the second test, I wonder if it has to do with the buffer failing? The first test was my CH standard based on deminieralised water, the second test was pool water.

As for the Palintest, I picked that up from a pool service guy basically brand new. He was going back to Lamotte spin lab so no longer needed it.
 
Hi Pat

Did you get to the bottom of why the Palintest result and the Taylor test results are so far out?

I have been having exactly the same issue over the last month since I started up my pool after the winter close.

I purchased a Palintest6 since the Taylor reagents are extremely expensive to source here in the U.K.

All the other tests are very similar between Palintest6 and Taylor ( FC/ CC / pH/ CYA /TA)

My current results are :-
FC 1.8
CC 0.2
pH 7.4
CYA 26
TA 102
CH 156 Palintest - 250 Taylor

Thanks
Ian
 
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