Can't Figure Out My Ph

[mkeogh]

I recently purchased a used spa and bought the BioGuard 4-way water test strips. When I compare my strip to the colors on the the back of the bottle my Bromine is ok, my Free Chlorine is between high and very high, my total alkalinity is ok, my PH is showing a hot pink but the colors on the back of my bottle go from orange to red, but no hot pink. Where am I at, too high or too low? Thanks.

[waterbear]

The problem is the test strips, get a good test kit. For bromine I recommend a Taylor K-2106

[Hillbilly Hot Tub]

I recently purchased a used spa and bought the BioGuard 4-way water test strips. When I compare my strip to the colors on the the back of the bottle my Bromine is ok, my Free Chlorine is between high and very high, my total alkalinity is ok, my PH is showing a hot pink but the colors on the back of my bottle go from orange to red, but no hot pink. Where am I at, too high or too low? Thanks.

High bromine will also give you a false high PH reading on test strips, ditto to water bear, get a good test kit, use the strips for quick in between readings

[mkeogh]

Thank you very much I just ordered the Taylor K-2106 test kit.

[poolandspaexpert]

The phenol red dye reacts with bromnine levels in excess of 8-15ppm and causes it to turn a hot pink or royal purple on most test strips / testers. You are well advised to purchase a Taylor K-2106 kit as there is not actual scientific method to get accurate pH readings from a test strip anyway. You can try using a product to remove the bromine or lower the bromine levels and try retesting if you need a solution working with what you have.

[waterbear]

Doesn't matter if it is a test strip or a drop based test such as the Taylor kits, high santizer levels cause interference to pH tests. Period. The ONLY way to get accurate pH readings with high sanitizer levels is by using a (properly calibrated) pH meter (which have their own set of problems and are not worth the trouble, IMHO). You can also dilute your sample with steam distilled water, which should have a 0 ppm TA and a neutral (7.0) pH and test. It is the TA of the diltuion water that is important and the TA should be 0 or as close to it as possible since higher TA will skew the pH test results. It does not matter as much if the pH is not exactly 7 as long as the TA is 0. The idea is to dilute the sample low enough so that youere is not interference from the santizer. Most decent pH tests (including strips) will work with sanitizer up to 10 ppm but give inaccurate results above that. (Strips have some other limitations that make them rather useless for testing, IMHO, and strips that do not give numbers but only OK, high, and very high are useless.) That is because the phenol red indicator that is used in the tests is converted into either chlorophenol red or bromophenol blue/bromophenol red (which is why bromine creates that purple color at high santizer levels). All these indicators test a much lower pH range than is found in pools so the color is the one at the top of the range even if the pool pH is 6.8! The colors are off chart and when bromine is used the color does not even exits on the comparator since it is from a mixture of two indicators that form a purple color. (Chlorphenol red tests a pH range of 4.8 to 6.8 while bromphenol red tests a pH range of 5.2 to 6.8 and bromphenol blue tests a pH range of 3.0 to 4.6 so at normal pool pH all of these indicators are showing high pH since for them it is! With bromine the red color of bromophenol red and the blue color from bromophenol blue creaate the purple color show. Interstingly enough. at the low end of their pH ranges all of these indicators turn yellow (as does phenol red).

Some people add a drop of two of sodium thiosulfate (chlorine neutralizer) to their sample before testing but this introduces it's own error since the pH of the sodium thiosulfate solution is quite high (9.6) and will skew the pH test results upward also. Taylor does use a halogen neutralizer in they phenol red solution but my understanding is that it is not thiosulfate so it does not have the negative impact on the pH of the sample being tested.