Use of Sequestering Agent with Pristine Blue

[vmscvp]

I have recently bought a new home that has an above ground swimming pool, 15,000 gallons. The pool was not maintained for over a year and was essentially a swamp. I finally cleaned it up with removal of organic material from the bottom, hyperchlorination, algicide, and filtiering 24/7 for about 2 weeks. In this process, I flocked the pool twice on advice from a pool store. Finally I had it totally clear and no stains on the vinyl liner.

The pool store recommended Pristine Blue system, and I followed the instructions and added Pristine Blue and it still was clear with no stains. One day later and after a severe thunderstorm that dumped 6 inches of ran in 2 hrs, the pool had a dark brown stain on the bottom. The stain could not be vacuumed up, and trying to scrub with a soft brush did not work. I took a water sample to the pool store.
FC: 0
CC: 0
pH: 8
TA: 140
CH: 250
CYA: 0
Cu: 0.5
Fe: 0.2
Phosphates: 300

The Pool store said it was probably iron and recommended lowering the ph and adding a sequestering agent and running the pump overnight. This is now 3 days later, and the water is still cloudy and the stain is still there. and the pump is still running 24/7. pH=7.4, Cu = 0.3, TA=90.

Any suggestions or recommendations?

 

[JasonLion]

There is absolutely no point in using Pristine Blue and sequestrant at the same time. Pristine Blue is a copper based system. Adding sequestrant will render the copper ineffective. It is also a really bad idea to allow the PH to get up to 8.0 while there are metals in the water.

I strongly recommend you stop using Pristine Blue and replace at least half of your water to get the copper and iron levels down to something reasonable. After doing that it might be possible to remove the staining (though not for sure if it is a copper stain, copper stains are sometimes nearly impossible to remove from vinyl).

 

[vmscvp]

Thank you for your response - you have confirmed my suspicion that using a sequestrant with a Cu -based "sanitizer" is counter-productive. My concern is that the well-water here is full of iron and what do I use to remove it in the pool when I re-fill. Also how do I switch from Pristine Blue back to chlorine?

 

[JasonLion]

There is no way to reliably remove either copper or iron from water aside from replacing the water with other water that does not contain metals. Sequestrant will sometimes remove some of the metals in the water, but that doesn't always work.

To switch to chlorine you either need to get both the iron and copper levels down below 0.3, or use sequestrant regularly to bind the metals in solution and prevent them from forming stains. In this case you will probably want to do both of those things, replace some water and use sequestrant.

Iron stains can be removed reliably. Copper stains come in a couple of different forms, some of which can be removed and some of which can't be removed without damaging the liner.