What each drop of Taylor R-0005 acid reagent means to pH?

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J

jmbuys

0
Jun 13, 2018
73
MA
Helping a friend w/ a pool at a new house. I brought my Taylor kit over and my water has always stayed between 7-8 pH range, always readable just using R-0004. But his water is dark red after R-0004 (44ml sample), looks darker than the red for a pH of 8. pH meter reports the water at about 8.5 (not sure how well calibrated it was). So I thought I'd try using some acid reagent (R-0005) into the 44ml sample.....3 drops of R-0005 brought the sample color down to 7.6. I don't use this reagent myself so looked up to see what each drop correlated to (for example does 1 drop of R-0005 reduce pH by 0.2-or something like that)...but the Taylor instructions just takes me to an acid demand table to show how much acid would be needed to drop pool into desired pH range based on pool size and the # of drops needed-(which is great we will need that info-but I was hoping to figure out what the current actual pH of his water is based on the fact that 3 drops of the acid reagent brought it down to 7.6-can I use the test to make that determination? For example if each drop does drop pH by 0.2 and 3 drops brought it down to 7.6 we would know his fill water is 8.2-but I don't see that type of correlation listed for that test.

Thanks
 
What is your friends FC level?

The pH test is invalid and reads high when FC is above 10 ppm.

Don’t chase an invalid high pH reading caused by high FC.
 
You can’t use the acid demand reagent the way you are thinking. It’s too concentrated to give a reasonable approximation for the starting pH. You can try putting your test results in to PoolMath with starting pH and ending pH to see how it correlates to the number of drops but what you’ll find is that it only takes a few drops of R-0005. PoolMath also only calculates pH and acid volume accurately when the changes are small (less than 0.3 units) so you’re going to get ambiguous results at best.
 
JoyfulNoise said:
You can’t use the acid demand reagent the way you are thinking. It’s too concentrated to give a reasonable approximation for the starting pH. You can try putting your test results in to PoolMath with starting pH and ending pH to see how it correlates to the number of drops but what you’ll find is that it only takes a few drops of R-0005. PoolMath also only calculates pH and acid volume accurately when the changes are small (less than 0.3 units) so you’re going to get ambiguous results at best.
Click to expand...
Ok thanks-makes sense and now understand why results only valid for the acid demand table based on large pool vol.
 
A guess is they don't try to give info like that because pH is logarithmic with a base of 10. Three drops starting at 9 affects pH about 10 times less than the same 3 starting at 8.

I suppose you could plug the numbers from the demand table into PoolMath and fiddle with starting pH with the added acid and pool volume constant, looking to make the final pH 7.6.

But what's the point? If pH is over 8.0, assume it's 8.2, add enough acid to bring it down to 7.6 or whatever you want. Wait a day. Test again. Rinse and repeat. PoolMath is your friend.

@ajw22's point about FC is a good one.

One other thing is that when the water is winter cold (I see you're in MA), a pH approaching or maybe a bit above 8 is fine because the danger of scaling is lower for cold water.
 
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generessler said:
A guess is they don't try to give info like that because pH is logarithmic with a base of 10. Three drops starting at 9 affects pH about 10 times less than the same 3 starting at 8.

I suppose you could plug the numbers from the demand table into PoolMath and fiddle with starting pH with the added acid and pool volume constant, looking to make the final pH 7.6.

But what's the point? If pH is over 8.0, assume it's 8.2, add enough acid to bring it down to 7.6 or whatever you want. Wait a day. Test again. Rinse and repeat. PoolMath is your friend.

@ajw22's point about FC is a good one.
Click to expand...
We were trying to figure out why pH was so high to begin with, so am looking at the fill water which also had the high pH-obviously I can't apply the acid to the fill water, so was trying trying to get an understanding of what he would be dealing with going forward using that fill water-so trying to calculate it just using the reagent results....but as pointed out can't use it like that.....will work backwards using the pool water-but that may or may not accurately reflect his ongoing fill water effects. I may calibrate the pH meter and see what it actually is.
 
mknauss said:
Fill water pH has virtually no effect on the bulk pool water pH.
Click to expand...
It's a newly filled pool and at least initially they appear closely linked in this case.
Backtracking from acid demand table for pool vol. and number of drops needed to get to 7.6, I took that acid amount and played w/ Pool Math to get an initial pH of 8.8.....calibrated meter is giving me 8.75....so just as an exercise for this situation, they seem to sync I see comments on other posts asking why demand table needed, and telling folks they can just use pool math...but If R-0004 gives result above 8-you don't know accurate starting pH for pool math and it becomes trial and error. The demand table based on reagent drops eliminates the trial and error for me.
 
PoolMath is most accurate with pH adjustments of 0.4 or less. Larger pH adjustments are less accurate. We recommend making pH adjustments of 0.4 or less increments.

Knowing pH is 8.8 is not real helpful since you don’t want to make a 1.0 adjustment.

With pH 8 or higher you tell PoolMath pH is 8 with a target of 7.6. Add acid, retest in about 30 minutes, and repeat until you have pH in the 7s.
 
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generessler said:
A guess is they don't try to give info like that because pH is logarithmic with a base of 10. Three drops starting at 9 affects pH about 10 times less than the same 3 starting at 8.

I suppose you could plug the numbers from the demand table into PoolMath and fiddle with starting pH with the added acid and pool volume constant, looking to make the final pH 7.6.

But what's the point? If pH is over 8.0, assume it's 8.2, add enough acid to bring it down to 7.6 or whatever you want. Wait a day. Test again. Rinse and repeat. PoolMath is your friend.

@ajw22's point about FC is a good one.

One other thing is that when the water is winter cold (I see you're in MA), a pH approaching or maybe a bit above 8 is fine because the danger of scaling is lower for cold water.
Click to expand...
To follow up on what is said above.
If you use 3 drops of acid demand to get to the right color for say 7.6 pH, if you put in 3 drops of Base Demand will not get you back to the original color of your pH test.
You need to make small changes in pH to ensure no overdosing whether going up or down the pH scale.
 
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Getting ph from demand test

Is there a way to determine the actual ph from the acid/base demand test? For example if it takes 6 drops to get the ph down to 7.6 what is the ph? 8.0? 8.3?
www.troublefreepool.com www.troublefreepool.com

pH base demand testing

Can anyone advise me on how many units of change is represented by 1 drop of pH base reagent? I'm using it to get a better pH calculation and it took me 4 drops to get down to around 7.0 where the color matched....adding back does this give me 7.4 or 7.6 or 7.8? :? Many thanks!
www.troublefreepool.com www.troublefreepool.com
 
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