Taylor K2006 acid demand vs PoolMath. Your opinion

[Paul.]

Hi all,
I just received my Taylor K2006.
I was playing around with the acid demand test and was wondering what everyone uses in order to lower their pH since the quantities in PoolMath vary from what is suggested from the Taylor kit

My results:
FC 14
pH 8.0, acid demand test 3 drops
TA 100
CYA 70
Calcium Hardness 340

PoolMath suggests 636g of dry acid to lower the pH to 7.5,
while the Taylor K2006 table suggests 1222g of dry acid.
Double the difference?

What are your opinions?

 

[Donldson]

I would tend to trust PoolMath, mostly because I don't have a kit with an acid demand test I do know that it figures in TA in the calculations, but I don't know if TA affects the acid demand test.

One good way to test this is to add what PoolMath suggests and test again in an hour or two. If you are at 7.5 then you know to trust PoolMath. If you aren't then you can add the remaining dry acid and rely on the acid demand test. Would like to hear the results on that myself.

 

[Richard320]

Your pH test results are going to be wrong because the FC is above 10. I'd wait until FC goes below 10, remeasure pH and TA and do the acid demand test, and see how they compare then.
Accurate pH test during shock levels with R-007? has pictures that show the color shift with high FC levels.

 

[Paul.]

I had the water tested electeonically at my pool store. The results are almost identical to what I got with the Taylor Kit. Can the high FC affect electronic testing of pH as well?

 

[pabeader]

yes. it effects the electronic tests too. Plus it was at the pool $tore so is suspect on it's face.

Pool math takes into account all the numbers you have in all the lines. The little book it the Taylor kit doesn't do that.

 

[JoyfulNoise]

I would tend to trust PoolMath, mostly because I don't have a kit with an acid demand test I do know that it figures in TA in the calculations, but I don't know if TA affects the acid demand test.

One good way to test this is to add what PoolMath suggests and test again in an hour or two. If you are at 7.5 then you know to trust PoolMath. If you aren't then you can add the remaining dry acid and rely on the acid demand test. Would like to hear the results on that myself.

The short answer is - yes the acid demand does take TA into account by virtue of the test itself.

All the AD test does is use a known concentration of HCl to add drop wise to your pH test. You count the number of drops needed to reach a color in the tube that is pH of 7.4 (sometimes 7.2). You then lookup your pool volume on a chart and then look across to the drop count (it's a matrix chart) and it tells you how much acid to add. Since the sample water contains your TA (and any borates that might buffer the pH change), then that's all wrapped up in the test.

Richard320 hits the nail on the head though, you have to have an accurate pH color read in order for the AD test to work.

I prefer to use PoolMath myself and I use the Acid/Base demand reagents to shift the pH colors during a pH test so that I'm sure I'm seeing the right color.


Sent from my iPhone using Tapatalk

 

[chem geek]

PoolMath approximates the pH acid/base calculations. The accurate amount is 695 grams of dry acid, but I suspect that your pH is actually higher than 8.0. If it were around 8.47 then that would require 1230 grams of dry acid to get to 7.5. This assumes no borates in the pool.

 

[Paul.]

Did the test by adding dry acid, a little bit less than what was suggested by the acid demand test. The pH is almost perfect. Will retry the experiment next time with ab FC in normal range. Ill let you know how it goes.

 

[chem geek]

Actually, it's not the FC that was the issue but the pH was probably higher than you could register in your pH test. It was 8.0+ and based on your results was probably around 8.5 in pH to start out.

 

[Crackerjack4u]

Also as Richard mentioned above in comment #3 "Your pH test results are going to be wrong because the FC is above 10."

It will be difficult to adequately adjust the pH with your FC at 14ppm because you won't know if the pH itself is high, or the reading is just high because of the high FC level, or both. That why we recommend adjusting it before increasing the FC above 10ppm, and then not checking it again until after the FC level is again below 10ppm because the level registering may very well be incorrect. So if you do want to continue to attempt to adjust pH with the high FC level please be aware of this, and attempt to compensate for the possible inaccurate readings as to not over shoot your mark.

I hope this helps and have a wonderful day.

EDIT: There is an excellent explanation in Comment #2 by Jason Lion of what happens with the pH reading when the FC levels are above 10. http://www.troublefreepool.com/threa...high-FC-levels