Cloudy Sample Water

[JPMorgan]

I am helping to maintain an indoor bromine pool for our HOA. I have noticed recently that when I add DPD powder to the water sample to test for bromine, the water sample looks a little cloudy. The water is clear in the pool, but when I add the powder to the sample it gets a little cloudy and is cloudy still after I add the drops of R003 to the sample. I'm wondering what might cause this. This is not the case when I test samples of the outdoor pool water (chlorine). MPS (Wipe Out) is sometimes used to shock the indoor pool. Could the MPS cause the water sample to turn cloudy and would it be better to use liquid chlorine to shock the pool? This pool also uses a DE filter whereas the outdoor pool is a sand filter. Thanks for any thoughts about this.

 

[Texas Splash]

It's been a few days since you asked this question. I wonder if @Donldson can help us out on this one?

 

[Donldson]

Hmm, I don't actually know why it does that, though I have seen it occasionally in chlorine pools too. Since the test involves color change it shouldn't have any effect on the validity of the test though.

 

[JoyfulNoise]

It’s due to the pH buffers used in the powder. The powder is, by weight, a majority of buffers and pH adjusters (the test needs to be conducted under slightly acidic conditions). The actual amount of DPD dye is only a percent or two by weight. There are phosphates in the buffer that can react with the mineral hardness in the water that causes the solution to get cloudy. As @Donldson said, it doesn’t affect the test results.

 

[JPMorgan]

Thanks guys. I appreciate the info.

 

[JPMorgan]

There are phosphates in the buffer that can react with the mineral hardness in the water that causes the solution to get cloudy.

Would this cloudiness be more likely to occur then if the CH in the water is on the high side?

 

[JoyfulNoise]

Would this cloudiness be more likely to occur then if the CH in the water is on the high side?

My water hardness is always high due to where I live. I have only seen “clear” DPD test when testing water that has no mineral hardness (softened tap water). Whenever I test my pool water, the sample is always “cloudy pink” and then turns “cloudy white” when titrating.