Did I mess up??

[aumfc]

Yesterday afternoon my water tested high pH and low salt in my 35k gallon SWG pool. So, I added a gallon of muriatic acid, which I've done a few times already this season, and 3 40lb bags of pool salt.

I added the acid first, all around the pool. About 15 minutes later, I added the salt by pouring it all along the edges. Some of the salt was in big, hard clumps, so I tossed them in. They stayed in clumps at first, but I knew they'd dissolve overnight.

This morning I go out to find staining on my plaster at the bottom. Did I screw up and add the salt clumps too soon after adding the acid, causing the acid to aggregate around the salt and "sit" on the plaster long enough to stain it? Is there a good way to fix the stain?

Picture of the pool bottom where there is no stain, followed by a picture of one of the stains. More noticeable in person.

 

[PoolGate]

Just taking a wag I'd say the muriatic somehow got saturated in the salt and sat in one spot. Not sure there is a fix for this. I've given up on my plaster being perfect long ago and just roll with it.

 

[mknauss]

I added the acid first, all around the pool.

Add acid at a pool return, pump running, at a slow rate (pencil sized stream). Brush the area after.
Not sure the salt had alot to do with it, might have.

Feel the area. Is it rough?

 

[JamesW]

Possibly iron.

Put a vitamin C tablet on a spot.

 

[mknauss]

Hmm -- are we looking at the yellow area or the blue area?? If yellow, James is right -- iron.

 

[aumfc]

The first photo is no stain. Second photo shows the stain. I'm not good with colors, I just know the stain is different than the surrounding plaster and not blue.

Before adding the salt and acid, there was nothing there and nothing else happened. No water was added to the pool, or anything else.

I'm not sure how it could be iron unless there is very small amount in the pool and it concentrated where the salt clump was. There is no return in that area.

Muriatic spilled on the concrete decking and made a similar-looking discoloration.

I used vitamin c tablets before to try to clean an iron spot. The iron spot went away but where the tablet dissolved there was a new stain. And I haven't been able to get it to go away.

What would you try? This is on the bottom in about 3 1/2 feet of water, but there is another stain like this in 6 feet of water at the bottom.

 

[JamesW]

Salt sometimes has iron.

Your other thread seems to point to iron.

Does your Fusion Soft 1400 SWG have a mineral cartridge?

If yes, that has copper and silver.

What caused my new pool water to turn green?

Our pool was plastered in white on Monday, 4/10. We filled the pool over about a week (due to low volume) from our well that passed through pH and iron filters. The water after the filters tested at 0 for everything other than a little hardness and 7pH. The water was clear other than dirt and...

www.troublefreepool.com

 

[JamesW]

I used vitamin c tablets before to try to clean an iron spot. The iron spot went away but where the tablet dissolved there was a new stain.

Picture of the new stain?

 

[JamesW]

I'm not sure how it could be iron unless there is very small amount in the pool and it concentrated where the salt clump was.

Why are you acting surprised about iron when your other thread clearly indicates iron?

Can you pull the filter cartridges and show what they look like before and after cleaning them?

 

[aumfc]

Why are you acting surprised about iron when your other thread clearly indicates iron?

Can you pull the filter cartridges and show what they look like before and after cleaning them?

I would be surprised because that photo was 2 months ago and the iron was addressed. There has been no discoloration since. There has been top off since then but that water goes through an iron filter where it comes out under 0.3ppm. So it would be diluted even more and well under the threshold to stain.

Also, the stains referenced in this thread appeared overnight after adding the muriatic acid and the salt. Something about adding one or both of those had to have contributed.

The stains are only where the big chunks of salt sat.

The only things that make sense would be:

A) the salt sat for a few hours in one spot while dissolving and caused the stains
B) the muriatic acid "pool" around the salt chunks in a high enough concentration to cause the stains
C) the salt reacted with the minute amount of iron possibly still in the pool water and caused the stains
D) a combination of B and C

Has anyone added muriatic acid and salt with large chunks at the same time and not had this problem?? If so, seems that would rule out A and B.

The two answers I'm looking for are 1) what caused this so I don't do it again and 2) the best way to remove the stains.

Thanks.

 

[mknauss]

What brand of salt did you use?

 

[JamesW]

The two answers I'm looking for are 1) what caused this so I don't do it again and 2) the best way to remove the stains.

Put a vitamin C tablet on a spot.

Salt sometimes has iron.

 

[JamesW]

Instant Stain

I don't have current test results yet, but hope someone can point out what possible interactions may have resulted in this. I don't close the pool for the Winter, but other than checking salt now and then I just let it run and verify balance of things before starting to use it again. Yesterday...

www.troublefreepool.com

 

[aumfc]

I hear you. As I said, the last time I left a tablet on the plaster it seemed to make it worse. I don't know if that's because the tablet stained it or because something similar to what happened here happened - meaning the small amount of iron in the water concentrated around the tablet and made another iron stain.

Is there any other instruction or tips for this? I assume I did something incorrect last time and I'd like to not do that again.

 

[JamesW]

Stairs stained yellow...Clorox salt?

Recently added a chlorine generator. I added Clorox salt. Now my stairs are stained yellow and my robot is collecting a Brown residue. Any thoughts?

www.troublefreepool.com

I was curious to see how well my in-floor jets would distribute the salt as an experiment so I basically dumped 2 bags in the same general location and went inside for about 1/2 hour. From doing a little bit of research, and although perhaps not the best practice this did not seem like it would be a problem to do. When I came back out to take a look there was what I could best describe as a forming rust stain around the perimeter of the existing pile of salt and with a major streak headed towards the main drain.

The fact that staining is randomly occurring leads me to agree with JamesW that this salt likely has yellow Prussiate of Soda (aka, sodium ferrocyanide, Na4Fe(CN)6) in it to act as an anti-caking agent. When the potassium ferrocyanide is added to pool water, the ferrocyanide anion (Fe(CN)64-, pale yellow) can be oxidized to the ferricyanide anion (Fe(CN)63-, dark red) and leave a stain. Over time, the ferricyanide will slowly breakdown to leave ferric iron (Fe3+) behind to form iron oxide/hydroxide stains.

Does your Fusion Soft 1400 SWG have a mineral cartridge?

If yes, that has copper and silver.

 

[JamesW]

As I said, the last time I left a tablet on the plaster it seemed to make it worse. I don't know if that's because the tablet stained it or because something similar to what happened here happened - meaning the small amount of iron in the water concentrated around the tablet and made another iron stain.

Vitamin C can clear up iron but it can sometimes cause copper stains.

Do you have a mineral cartridge in your Fusionsoft?

 

[aumfc]

Stairs stained yellow...Clorox salt?

Recently added a chlorine generator. I added Clorox salt. Now my stairs are stained yellow and my robot is collecting a Brown residue. Any thoughts?

www.troublefreepool.com

It does have the mineral cartridge according to Google.

I'm going to try a different vitamin c tablet. the last one was chewable. maybe that's why it didn't dissolve well.

 

[aumfc]

What brand of salt did you use?

Clorox from Lowes.

 

[mknauss]

Clorox salt is known to cause iron stains.
Likely that.

From our Wiki
Clorox Pool Salt has been reported by multiple members to stain pools.[7][8][9][10] Morton's Pool Salt has also been reported to have some bad batches with dirt that caused staining.

 

[PoolGate]

I have the below which is effective for removing some surface stains.

https://www.amazon.com/gp/product/B004VU8GNI/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1