Clear Choice TA titration drops vs 4 in 1 drops?

tomfrh

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Jan 30, 2018
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I get 138 g/1000L /84 *100 /2 = 82 g / 1000 L = 82 ppm TA.

Ok, so my solution was really only 82ppm. Thanks for correcting.

So the Aussie gold test starting to fade at 8-9 drops makes sense, yeah? That’s the point at which the CCL test is already fully pink?
 
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mgtfp

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Seems to match the indicator chart, that it really is the first fading that counts.

I think the CCL indicator is easier to get right, much sharper colour transition, rather than a long fading followed by a colour change once you're too far.

I reckon the AG might work better when doubling the sample volume giving 5ppm per drop. Not that 5ppm is required, but like that you should always see the fading followed by the colour change. With the standard sample size you will sometimes see the fading followed by the colour transition and sometimes jump straight to the colour change, making the test less standardized compared to CCL.
 

tomfrh

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In pool math it says you need 176 to raise TA by 100ppm, but also says the effect of adding 167 will raise by 100ppm? It says the effect of adding 176 is to raise it 105ppm

Why are the numbers different? 167 vs 176?
 
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mgtfp

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I suspect there are some rounding issues, or lookup table issues.

The exact value (using more precise molar masses of 84.006 and 100.088) is 167.864g (to raise TA by 10 in 10000l). This is from the hand calculation and also confirmed with Chem geek's PoolEquations spreadsheet, which is the basis for PoolMath.

But effects of adding gives 10.0 (it rounds TA to natural numbers above 10, and to .1 below 10) for values between 167.1g and 176.2g.

Not sure how the algorithm in the main section works. Since it kind of works backwards to give an estimated amount to be added, it just gives a value that yields the desired change with the required precision. Since you never know your pool volume that precisely, it doesn't really matter.

I guess, to mix a reference sample, you either have to crunch the numbers by hand, or use chem geek's spreadsheet (a forum search will get you there, but it takes a while to master it).

PoolMath has been designed to be used as easy as possible with a precision that is sufficient for day to day pool use.

The effects of adding is pretty exact where simple equations are available, but still rounds the end result in a way that's appropriate for pool use, and it doesn't always consider cross effects from other water parameters, like impact of TA, CYA, Borates on pH calculations, it uses simplifications that work in typical parameter ranges. Only chem geek's spreadsheet solves the chemical equilibrium equations "from scratch" - I love it, but it's too complex for a general role-out.
 

mgtfp

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tomfrh

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Not sure how the algorithm in the main section works. Since it kind of works backwards to give an estimated amount to be added, it just gives a value that yields the desired change with the required precision

Yes it the main section I’m wondering about. The “effects of adding” gives the values you’ve mentioned - 1680 g/10000L, whereas the main section gives values of 1758g/10000L to produce the same 100ppm change. Splitting hairs at this stage I know.

As for the tests accuracy, the Aussie gold is seeming ok from what I can see.

Re. Reference mixes, I’ve received bad references from CCL before, so would just as happily mix my own, now that I know the right quantities.
 

AUSpool

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As for the tests accuracy, the Aussie gold is seeming ok from what I can see.

Re. Reference mixes, I’ve received bad references from CCL before, so would just as happily mix my own, now that I know the right quantities.

I do not believe that the TFP community would be happy to provide credible advice based on test results provided by non recommended kits for the very reason highlighted in this thread. Poor indicator selection can easily lead to inconsistent results.

A halve decent standard solution just cant be prepared with any usable accuracy outside of lab grade conditions and equipment.
 

mgtfp

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I do not believe that the TFP community would be happy to provide credible advice based on test results provided by non recommended kits for the very reason highlighted in this thread. Poor indicator selection can easily lead to inconsistent results.

Agree. I'd consider the Aussie Gold (or the Blue Devil) as a backup test for a sanity check should the CCL test show an implausible result (like you're expecting a result in the 70-90 range, and the test shows 30 or 150, or something like that).
 

tomfrh

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Jan 30, 2018
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The blue indicator seems ok to me. You can pick it beginning to fade within 1 drop accuracy, and it seems that beginning to fade is the correct point to measure.

If there’s some other reason not to use it I’d be interested to hear it.
 

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mgtfp

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What we have seen is that the end point I'd reached when it turns clear, but eventually it will turn blue when you are too far. That creates a lot more uncertainty, you can't just say (as with the CCL-test) "You're done when an extra drop doesn't change the colour anymore, and don't count that last drop." There is always this uncertainty left, if you missed the clear bit, when it jumped straight to the colour change.

Also, the whole support on TFP is based on members using the same test method. That will give others the confidence to say "add acid" or something like that based on a test result. They won't know how to interpret the endpoint in the Aussie Gold titration, and even if they know, they won't know if the member seeking help knows. TFP published detailed guidelines for Taylor-based tests that everyone can refer to. They can't (and won't) do that for every single test on the market.

It's up to everyone to do whatever they want with their pool, but helping each other is based on a foundation of tests that we all know.
 

tomfrh

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Jan 30, 2018
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Australia
To go back to the start of this thread - the primary problem was the Clear Choice titration bottle.

I have got a new TA kit from CCL and the new titration bottle gives normal results (agrees with CcL’s TA standard and says pool TA is 100ppm), whereas using the old CCL TA titration bottle (with everything else fresh) gives the same very low result (TA 50-60ppm) I initially encountered.

Interestingly the Aussie gold test is starting to change colour at around 80ppm when measuring a sample that CCL says is 100ppm, so perhaps the first hint of colour change isn’t the best way to record it after all. Doing it by the book (turns clear or yellow) agrees more closely with CCL. This time around anyway....
 
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