Pristine Blue to Chlorine

[RaviePoolGirl]

This post is for my Mother's Pool. I found out from her that last season she used Pristine Blue instead of chlorine for a cheeper alternative. After much reading and educating her that Pristine Blue is not a sanitizer, but just an algicide, she will be making the switch back.

I wouldn't think she would need to drain any of the water for removal of Pristine Blue, just start BBB method as backwashing will slowly reduce the level that may be present. I already have her onto a good test kit TF100.

I am more curious if she may encounter cloudy water as she begins chlorine sanitation again, considering that last season she has had many bathers and I am sure a buildup of organics that will still be lurking. She is still winterized and has not opened as she is in Michigan. She has an 19,000 gal round AGP.

Any experience with this? I just want to give her an idea of what she may expect.

 

[JasonLion]

The main thing is to test the copper level and either insure that it is below 0.3 or use sequestrant. Copper levels of 0.3 or higher can form very difficult to remove stains when chlorine is added unless you are using sequestrant.

 

[chem geek]

At least it's an AGP pool so I presume has a vinyl liner. Plaster pools get stained more easily. Also, if you find that the copper level is higher than Jason mentioned, not only use a metal sequestrant, but also try and keep the pH from getting too high. It is the combination of higher metal ion concentrations and higher pH that causes metal staining though extremes of either can also cause a problem. For copper, it's not the chlorine itself that is the issue, but the fact that the pH rises when adding a hypochlorite source of chlorine and that in a pool with CYA in it such rise is even higher. The use of 50 ppm Borates helps to minimize that rise in pH if you find this is a problem.

 

[RaviePoolGirl]

Yes it is a vinyl lined pool.

If a sequestrant is used to bind any copper present, can it be tested for?

 

[JasonLion]

Yes in most cases, most of the copper tests still work correctly when there is sequestrant in the water.

 

[RaviePoolGirl]

So then, if it is necessary to add a sequestrant, she will add it based on the size of her pool (obviously). Can we assume that added correctly, all the copper will be bound until it is removed from the pool by backwashing?

Thanks,
Bobbie

 

[JasonLion]

The challenge is that sequestrant breaks down slowly over time, so you need to constantly (usually weekly) be adding more. Other than that, you are correct.