Metal stains

[adubbs09]

We had our pool replastered last spring. In the summer last year I noticed a few small metal stains and was able to remove them with vitamin C. One removed immediately and the other made it look worse and spread but eventually disappeared. This year there are more than last year. They are relatively small. What should I be doing to get rid of these for good? I have had the water tested for metals and don’t really have any metals in the water but obviously there are some.
Thanks
Adam

 

[Texas Splash]

It sounds like you may have both some iron and copper. The Vitamin C would of course lift the iron, but might have aggravated the copper for a short time. How these get in the water is a bit of a mystery. Sometimes owners add products that contain metals. Other times it's as simple as yard landscaping and some fertilizer, pesticide, or some other material gets blown in. As long as they are isolated and not widespread you should be okay with spot treatments.

 

[adubbs09]

It sounds like you may have both some iron and copper. The Vitamin C would of course lift the iron, but might have aggravated the copper for a short time. How these get in the water is a bit of a mystery. Sometimes owners add products that contain metals. Other times it's as simple as yard landscaping and some fertilizer, pesticide, or some other material gets blown in. As long as they are isolated and not widespread you should be okay with spot treatments.

Thank you! The vitamin C lifts the stains but then do I need to sequester it or use something else to remove it from the water so it doesn’t come back? Any suggestions?

 

[Texas Splash]

The vitamin C lifts the stains but then do I need to sequester it or use something else to remove it from the water so it doesn’t come back?

If it's just an isolated stain or two, or three, it should be fine. Something might've just landed on the pool floor and the Vitamin C lifted it into solution. That's different than say a pool that is filled from a well with iron actually in the water source. So in your case of isolated markings, if they lift you should be good. Now if a stain returns to the exact same spot, then we need to discuss further.

 

[Flot]

I just logged in to post almost exactly the same thing, so please excuse the hijack. I am going to add on to this thread in case we have other similarities. OP's pictures even look much the same as mine, although I have about 30-40 stains which I can only describe as obviously rust.

These popped up about 3 weeks ago (just before I left on vacation) and at the same time, I realized my SWG wasn't making chlorine and my chlorine levels were super low. At first I thought something had blown into the pool, then after brushing did nothing, figured they were some sort of algae spots so I did what anyone would do, threw in a couple bags of salt, cranked up the SWG, tossed in some shock and left for 2 weeks. Well when I got back, all the stains were waiting for me.

Here's what I can say:
- 90% of my staining is in the deep end of the pool, 10% in the shallow end, and there is essentially 0 on the walls
- Vitamin C (at least, me in the pool scrubbing with a couple of pills I had) had little to no effect on them
- Rubbing with a Chlorine puck had little to no effect
- Brush scrubbing does absolutely nothing
- Dabbing muratic acid on the plastic drain cover (photo below) lightened the stains a little bit

Well today, my local pool store (which is pretty terrible job and uses an automated water test system) says I'm at 0.1 ppm Iron and 0.3 ppm copper. Previously the only things they had identified as being out of whack were low TA, (I also threw in 5 lbs of alka up before vacation) and I usually have a PH around 7.8. Bizarrely, despite me complaining about what I thought were rust stains, the friendly associate didn't mention the fact that the first thing his automated computer printout suggested was removing the metals. It DID flag my TA at 46 which is a record low for me and recommends adding 10 lbs, as well as my Free and Total Chlorine at 12.7. They're reporting PH of 7.8 but I don't trust that.

I did some reading and between my high chlorine and low TA it seems like adding any metal sequestrants at this time would be a terrible idea?

I did realize sometime a few years ago that their computer system - bizarrely - will cap some results. I feel like in 2021 I had an issue where they continually recommended I add 12-16 oz of acid even though I needed much more than that. So I worry that my PH might actually be higher than 7.8 but I can try to sanity check that with a test kit tomorrow.

I was at my wits end trying to figure out how metal could get in the pool, but I have changed lawn services this year and noticed that they throw black soil everywhere when they edge my patio. And when I cleaned my filter today, the element was black with dirt that quickly and easily washed off, and the filter media itself has some rust staining on it. The only place I can see any ACTUAL rust in the entire system is the stainless metal bar that the hayward cartridge filter top cranks down on, about 5" of that is fairly rusted.

Ideas for me? Does it make sense that all my problems could be from soil thrown into the pool? What on earth do I do to remove dozens of 1/4" rust spots?