TA Test - Me vs. Pool Store(s)

[TSH]

I use Ben's PS-233 to test my own water. I have never had a problem with bouncy pH or TA. When I test I keep dropping the R-009 reagent until the colour stops changing. It goes from green to purple and then to red and then to a very pale red and doesnt move off of that colour. It goes to purple at about 6 drops, to red at about 8 drops and then to pale red at 10 or 11 drops and additional drops make no difference.

I thought I was to keep dropping R-009 until there was no further colour change. This always gets me to 100 or more.

Two different pool stores also tested for me this weekend - one said TA was 75 another said 80.

The one that said 75 said it was too low and that I needed to get some buffer in asap because my water was acidic and I would start stripping copper out of the heater and it would wipe out the heater. I suspect that this is not correct, given that this store also told me my pH was fine (7.8).

Anyways, looking for some insight on the home test vs. the two pool stores and which is likely to be more accurate and what, if anything, I need to do, ie. add baking soda to bring TA up?

Thanks.

[waterbear]

Trust your results. According to Taylor you are supposed to add drops until there is no further color change by adding an additional drop and to not count that last drop. The PS-233 was basically a rebranded Taylor kit with Taylor reagents.
The pool store is wrong.
If anything I would consider lowering your TA a bit if (and only if) you are dealing with pH rising and you are chlorinating with bleach or liquid chlorine, cal hypo, or lithium hypo.
If you are using trichlor tabs for chlorinating (or dichlor granules) then your TA is fine at 100 ppm and could even be a bit higher.

At any rate, If you are using bleach, liquid chlorine, or other unstabilized chlorine then a TA of 75 is certainly not too low and is close to the APSP recommendations for TA as taught in CPO courses of 80 to 100 ppm for unstabilized chlorine and 100 to 120 ppm for stabilized chlorine, gas chlorine, and bromine.

Bottom line, the pool stores you are dealing with don't know beans about pool care! Is that a surprise?

I will bet that the pool store that got 80 ppm is using a Taylor titration and not carrying it out to endpoint and the other one is using some sort of colorimeter to read either a reagent vial or a strip and that your normal FC is above 3 ppm. In both these cases the results would not be accurate.

[shadowman]

Hmmm...I'm confused, :confused: My Taylor kit says to add R-0009 until it changes from green to red. Why the difference?

[TSH]

Thanks Waterbear. I suspected at least one of the stores was off when he said the water was acidic based on my "low" TA, yet my pH was fine (actually a touch at the high-end with 7.8).

I have a salt water system. Salt reading is currently 2900 and I have the system set to 20% chlorine generation. I use a powdered acid (ph Down) when I need to bring pH down (it does tend to creep up, albeit slowly). My FC was about 2 when the samples were taken Saturday.

[waterbear]

Thanks Waterbear. I suspected at least one of the stores was off when he said the water was acidic based on my "low" TA, yet my pH was fine (actually a touch at the high-end with 7.8).

I have a salt water system. Salt reading is currently 2900 and I have the system set to 20% chlorine generation. I use a powdered acid (ph Down) when I need to bring pH down (it does tend to creep up, albeit slowly). My FC was about 2 when the samples were taken Saturday.
With a SWG try lowering your TA to abut 70-80 ppm. You should find that helps with the pH rise. Also make sure your CYA is at about 80 PPM. That will also help with the pH rise.

[waterbear]

Hmmm...I'm confused, :confused: My Taylor kit says to add R-0009 until it changes from green to red. Why the difference?
Taylor has a LOT more info on their website. This is where it says to keep adding drops until one more drop doesn't produce further change and then not count the last drop.
http://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=35

[CarlD]

Thanks, Evan. That's a fine detail I didn't know.

The moral is you MUST process what pool store guys say and do a reality check on them.
How can a pH of 7.8 be low?
Saying that the T/A of 75 would could acidity to eat your copper means the PSG (Pool Store Guy/Gal) doesn't know what T/A is.

Hey! I like that! Don't get Poolstored by a PSG :p!

[TSH]

Yup - that is exactly what I thought. I will stick with my testing and try to bring the TA by splashing and pointing the jets up at the surface.

I will have to test my CYA - I doubt it is as high as 80, but I do have some stabilizer hanging around that I can add.

Thanks all.

[aylad]

Splashing and pointing your jets up will raise the pH, not affecting the
TA. If you're trying to lower your TA, you use acid to drop the TA and the pH will drop with it....then you aerate the water with splashing and upward jets to raise the pH back up without raising the TA.

Janet

[TSH]

Thanks for clarifying.