Couple testing questions using TFP 100

[lovingHDTV]

1. My hardness test never turns blue, but does turn a very light purple. Buggsw linked to a Tayler document earlier that says to put 5-6 drops of titrant prior to testing. How do I figure out which reagent is the titrant? I'm thinking it is the second reagant R-0012.

2. I'm having difficulty reading the PH test. The color appears to remain the same no matter the ph. It is a very light pinkish color. I thought it matched 7.2 but took my water to the pool store and it was 8.0! This made more sense as I've been putting lots of bleach in the pool and no acid. I then used my old kit (Rainbow brand) and it showed 8.0 also. After adding acid to reduce ph I tested again with the Taylor kit and the color had not changed. I then tested with my old kit and it showed 7.6. I'm keeping my FC at 15-20ppm trying to get it to stop using bleach. Is this causing issues? I know that for my old kit I have to add two drops of CL neutralizer, but the TFP-100 does not call for this.

Any help much appreciated.

thanks,
dave

 

[JasonLion]

The titrant is the one you count drops of to get the reading, R-0012 for the calcium hardness test.

The Taylor PH test is known not to work at high chlorine levels. There is a chlorine neutralizer you can use, but it doesn't come in the TF Test Kit.

 

[lovingHDTV]

Do you know of where I can found out more info on this? With my high FC it appears that I wont ever be able to use the Taylor PH test without neutralizer. I'm sure I can find some to buy, but how much should be used?

Maybe we could also get updated instructions for high FC pools and the TFP-100 kit?

thanks,

 

[CaOCl2]

Do you know of where I can found out more info on this? With my high FC it appears that I wont ever be able to use the Taylor PH test without neutralizer. I'm sure I can find some to buy, but how much should be used?

Maybe we could also get updated instructions for high FC pools and the TFP-100 kit?

thanks,

Well, you can maybe use the thiosulfate from the alkalinity test but that can probably skew the results as it is acidic.

 

[JasonLion]

The Taylor PH test is compensated up to a FC level of 15. Above that it will read incorrectly. For FC above 15 you can partially compensate by adding two drops of R-0007 (thiosulfate). That should eliminate the interference but will cause the PH to read somewhat higher than it really is. Taylor mentions this here and there in their manuals but seems to not actually recommend doing this because it is difficult to know just how much the R-0007 will shift the PH (which depends on the alkalinity and possibly other things).

 

[Guest]

Actually, the Taylor pH reagents are the least likely to have interferance from high sanitizer levels. The chlorine neutralizer is built in and the color comparators are compensated for this so the results are accurate. What happens with phenol red when the sanitizer level is hight is that it converts to clorophenol red. This has exactly the same color changes as phenol red but tests a much lower pH range (4.6-6.8). The Rainbow reagent is notorious for not being accurate at high sanitizer levels. I would trust the Taylor reagent. Since I do not know what kind of reagents your pool store uses I cannot comment on their results but I suspect the same thing is happening.
When the phenol red converts to chlorphenol red all the purple color means is that your pH is 6.8 or above since that is the highest pH that chlorphenol red can test!

It's pretty much impossible to test pH when the sanitizer is much above 10-15 ppm unless you use a pH meter. Don't even worry about it if you are shocking the water until the FC levels have dropped back down. Also the TA test can have some interferance with high santizer levels also. One of the indicators can bleach out.

To eliminate the interferance from metals on the calcium hardness test (purple endpoint instead of blue or 'purple floaties' in the sample) put in 6 drops of the third reagent (the one you normally count the drops on), swirl for about 30 seconds, put in your 20 drops of the first reagetn and swirl for about 20 seconds, put in your indicator and swirl until the color is an even pink, then start your titration (drop count) BUT swirl the vial for 20-30 seconds after EACH DROP!. The test can take a long time to do if you calcium is high. As an alternative, get one of those magnetic stirrers from CaOCl2 and add the drops about 5 secconds apart. When the titrant is completely mixed you can see the color change much better and the 'floaties' don't interfere as much. Keep adding drops until the color changes to blue and one more drop does not cause any additional color change. Remember to count the first 6 drops you added but don't count the last drop that didn't produce any change. For example, lets say you put in the initial 6 drops, added the calcium buffer and indicator and began your titration. You added another 18 drops of titrant and the color changed to blue, you added a 19th drop and there was no other color change. Add the first 6 drops to the 18 drops for a CH of 240 ppm.

 

[lovingHDTV]

waterbear,
I tried the new CH method and it worked very well. I got a nice blue color instead of a pale purple with floaties.

Since my CH is >600ppm I also modified per Taylor instructions by using 10ml sample instead of the 25ml sample. This only required 25 drops instead of 63.

I also tried adding 2 drops of R-0007 for my PH test and actually got a color that was between 7.5 and 7.8. All other tests resulted in a light pink color that I could not match to anything.

thanks for the help,

 

[Guest]

I would like you to try a little experiment for me. Using the taylor pH reagent I would like you to add a drop at a time of the total alkalinity titrant (3rd reagent) cap and mix and letme know of the color changes. The acid should cause the color to change to a lower pH value. Also try this after you add the neutalizer and see what the difference is.