Purple water

[Johneace]

Hello all, I recently drained my gunite/plaster pool. I had a white powdery type substance stuck to the surfaces. After some severe scrubbing with a scouring pad, I got about 90% of it off. After some thought, it's possible that it was a lime scale. That however is not thereason for this post. Once I started filling the pool back up, I noticed the water was purple. You can imagine the shock on my face when I was watching this happen before my eyes. The pool water being filled with was city water. It was Saturday afternoon near 5pm, I collected a sample and went to the only pool store open at that time, Leslie's. Long story short, there water testing computer was broke and had no insight as to what it could be. I rolled the dice and bought a bottle of metal out, added to the water and next morning the pool was clear. I still can't understand how brand new water would be turned the color of faboluso. Does anyone have any insight as to what could have been the problem?

 

[Jimrahbe]

John,

Let's see what Matt has to say... Calling @JoyfulNoise

Thanks,

Jim R.

 

[Texas Splash]

I still can't understand how brand new water would be turned the color of faboluso.

I'm going with manganese. City water doesn't always equate to perfect water.

 

[C3Cl3N3O3]

Beats me, but that looks cool!

 

[jedigrover]

Purple is generally manganese. Did your scouring pad have any kind of cleaner in it?

Edit:
Manganese is often present with iron in well water. And water treatment plants sometimes use potassium permanganate (which you may remember from chemistry class is a purple similar to your water). Wikipedia entry on it below:

Water treatment​

Potassium permanganate is used extensively in the water treatment industry. It is used as a regeneration chemical to remove iron and hydrogen sulfide (rotten egg smell) from well water via a "manganese greensand" filter. "Pot-Perm" is also obtainable at pool supply stores and is used additionally to treat wastewater. Historically it was used to disinfect drinking water[9][10] and can turn the water pink.[11] It currently finds application in the control of nuisance organisms such as zebra mussels in fresh water collection and treatment systems.

 

[Johneace]

Purple is generally manganese. Did your scouring pad have any kind of cleaner in it?

No just a plain kitchen scrubber, no chemicals. I appreciate the feedback.

 

[Griswald]

Pride month pool!

 

[JoyfulNoise]

Hmmmm … I’d vote AGAINST manganese because it usually turns water black, not purple. I suppose a very faint black could yield purple …

Any copper containing products used in this pool ? Copper cyanurate is purple colored. But that usually occurs when copper and CYA are both very high ….

 

[dfwnoob]

You didn't use any cleaning chemicals? I see what looks like a bottle of CLR in the 5th picture as well as a bunch of suds.

 

[Johneace]

You didn't use any cleaning chemicals? I see what looks like a bottle of CLR in the 5th picture as well as a bunch of suds.

The CLR came into play when I got to the areas that I couldn't reach at the end, to see if that would help. I might have used a quarter of a bottle of spray. Everything was rinsed and used a shop vac to get all of the water out.

 

[JoyfulNoise]

I’d say your likeliest suspects are either manganese or copper. The only way to know for sure is to have a water sample tested by an independent lab to see what’s in there. I’d send a sample of the pool water as well as a sample of the fill water from the tap you used. The addition of sequestrant and subsequent disappearance of the color points to a metal contamination.

Keep an eye on the water as the sequestering agent will break down over time causing the metal to come out of solution. You may notice staining or the return of color to the water.

 

[Johneace]

Any copper containing products used in this pool ? Copper cyanurate is purple colored. But that usually occurs when copper and CYA are both very high ….

Before we drained the pool, we used algeacide in the water that did contain copper. However the water that WAS in the pool never turned colors. The reasons that we drained the water was we had to floc the pool once a week because of the high phosphates that we have been experiencing. Also the water was quite warm and from I've learned since being a pool owner is, warmer water is harder to keep up with.
I'm guessing that there was some residual chemicals in the sand filter that may have caused this.

 

[Texas Splash]

The reasons that we drained the water was we had to floc the pool once a week because of the high phosphates that we have been experiencing.

That speaks volumes. Pool store advice perhaps? Regardless, if you elect to exchange the water again (which I would recommend), do so with the knowledge that phosphates are irrelevant to clear water and are primarily a tool the local store uses to sell junk for $40 a bottle that you don't need. Floc is almost never recommended here at TFP due to complications. Follow the link below and be sure to test your own water with a TF-100 r Taylor K-2006C test kit. It's that simple.

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!

www.troublefreepool.com

 

[SoDel]

My bet / guess would be cyanuric acid residue in the plaster combined with excessive copper in the water. The fill water would extract the cyanuric acid back out of the plaster until equilibrium and combine with copper to make purple. Do you know what CYA levels were before you drained it?

 

[chazas]

That speaks volumes. Pool store advice perhaps? Regardless, if you elect to exchange the water again (which I would recommend), do so with the knowledge that phosphates are irrelevant to clear water and are primarily a tool the local store uses to sell junk for $40 a bottle that you don't need. Floc is almost never recommended here at TFP due to complications. Follow the link below and be sure to test your own water with a TF-100 r Taylor K-2006C test kit. It's that simple.

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!

www.troublefreepool.com

Listen to this advice. Not to say that people following TFP methods never have issues - we do - but for chemistry issues the solutions are often much simpler than the path you appear to have been led down.

 

[Johneace]

My bet / guess would be cyanuric acid residue in the plaster combined with excessive copper in the water. The fill water would extract the cyanuric acid back out of the plaster until equilibrium and combine with copper to make purple. Do you know what CYA levels were before you drained it?

My CYA has been running on the low side this season so far. I've only used test strips(don't hate on me please, I just signed yesterday on TFP's site and have learned how unreliable the strips are now) and it has been telling me my CH and CYA have been low. Even after adding about a pound at a time of CYA granulars at a time it still tells me it's low. Thinking back now, that is certainly possible of what you are saying about the plaster and CYA. I'm going to order a proper water test kit today

 

[JamesW]

Maybe manganese or copper cyanurate.

Can you show a picture of your cartridges from the filter?

 

[Johneace]

Maybe manganese or copper cyanurate.

Can you show a picture of your cartridges from the filter?

I have a sand filter

 

[JamesW]

I have a sand filter

Is there any color in the backwash water?

 

[Johneace]

Is there any color in the backwash water?

No sir, nothing out of the ordinary. It only lasted for that day, the next day was clear as a bell