Orangish, organic staining in AND out of water... What in the world?

[JLMM]

Hi all... I'm still pretty new to pool chemistry, but in the last week I felt like I'd pretty much figured things out. I SLAMmed my pool, which got rid of some minor algae growth that occurred because I wasn't maintaining the pool correctly. Everything was great after that, daily testing had good numbers, water crystal clear.

Yesterday, mid-morning, I tested the water:

FC: 6
CC: .5
PH: 7.4
TA: 140
CYA: 30

We swam all day and the water was great. I noticed a very small patch of orange/rusty-colored staining on the wall near my ladder in the deep end, but figured it was just a weird patch of pollen or something. This morning I went out to check the pool and the patch of staining was much larger, and when I walked around the pool I found several other patches of it as well. They seem to be in pretty random spots - not just in shady spots (pool gets full sun in any case). I tested:

FC: 1
CC: .5
PH: 7.4
TA: 140
CYA: 30

I immediately dumped in enough bleach to raise FC within range, and I overshot a bit because we're expecting several days of rain. That got me to FC of 9.

I brushed the heck out of the spots, but they do not budge. Not even the slightest bit of dust comes off them. I tried putting a chlorine puck on one, and it totally eliminated the spot. Tried again in a few other places - also successful.

Then I happened to notice that in some white places outside of the water - places where water from the pool would drip or splash, like near the stairs - there was the same staining, in splotches and small spots. Rubbed the chlorine puck on those and they disappeared.

What in the world could this be? I'm hoping against hope that it's not mustard algae. Do I need to SLAM the pool? Help!

 

[Richard320]

It might be rust.

Typically, you try the Vitamin C tablet first. If it's metal, it fades. If not, then the puck. Pucks are very acidic, so they could give you a false positive for metals.

 

[JLMM]

Thanks for the suggestion. I just crushed up some of my kids' Vitamin C tablets in a sock, and weighted that down on one of the spots for about 5 minutes. No change. I also scrubbed one against one of the spots on the deck, hoping for something there, but no dice.

Before I found this forum, we had a pool guy open the pool for us and he shocked it - I have no idea how high, but it reeked of chlorine. And all the water in the pool turned light orange for a couple days right after that. These spots are a similar sort of color. I'm not sure if that could be related or not... The spots in the pool may not even be related to the spots outside of the pool, for all I know.

*sigh* I should probably SLAM again, eh?

 

[Richard320]

Thanks for the suggestion. I just crushed up some of my kids' Vitamin C tablets in a sock, and weighted that down on one of the spots for about 5 minutes. No change. I also scrubbed one against one of the spots on the deck, hoping for something there, but no dice.

Before I found this forum, we had a pool guy open the pool for us and he shocked it - I have no idea how high, but it reeked of chlorine. And all the water in the pool turned light orange for a couple days right after that. These spots are a similar sort of color. I'm not sure if that could be related or not... The spots in the pool may not even be related to the spots outside of the pool, for all I know.

*sigh* I should probably SLAM again, eh?

Run an overnight loss test; that will tell you whether you need to SLAM. It may still be metals. I'd leave a bunch of vitamin C on a spot for half an hour.

 

[JLMM]

Will do. Thanks!

 

[JLMM]

Okay, so I *think* it passed the OCLT? My test last night gave me a higher FC reading than the one I'd taken in the afternoon, but I didn't test from my usual spot (Test Spot A) on account of a thunderstorm rolling in. Instead, I tested from the spot closest to my house (Test Spot B), which is right next to the return where I pour in the chlorine. I figured that was why the level was elevated, and I made sure to test from that spot this morning. Then I double-checked it by testing in my usual spot, too.

Yesterday afternoon (overcast day): Test Spot A
FC: 9
CC: .5

Last Night: Test Spot B
FC: 11
CC: 0

This morning: Test Spot B
FC: 9
CC: 0

This morning: Test Spot A
FC: 8
CC: 0 - .5 (pink was so faint I wasn't sure if I was really seeing it)

So I know that Test Spot B didn't pass the OCLT, but the other spot did, and that was from a reading taken yesterday afternoon. So I'm inclined to think that the elevated reading was a fluke and that the pool, overall, is sitting around 8.5?

The stains seem to be fading on their own under the higher chlorine levels. There's nothing I see that turns white, and still nothing brushes off those spots. They're just disappearing. Rest of the pool looks great. I'm not quite sure what to make of it.