Salt Water Stain Removal

[Nelsonto]

I have a 10K fiberglass pool that has iron stains. Although Ascorbic acid works great it makes it difficult to manage the chlorine levels (even with the Hayward SWG). I want to try the stain removal process described in the sticky on the forum but it mentions using Jacks Magic Pink Stuff. After I ordered that I noticed printed on the back of the bottle it states that for salt water pools Jacks Magic Purple Stuff should be used. Is that correct?

[PoolDoc]

1. Use the products listed. Our selection is based on actual chemical ingredients, rather than on the Jacks Magic marketing plan for product differentiation.

2. BUT, get a K2006 kit, and learn to use it, FIRST. There's no point in removing stains till you can successfully measure and manage the basic water chemistry parameters. Stain removal (and continuing control) REQUIRES you to manage water chemistry on a continuing basis. (http://pool9.net/tk/)

3. Ascorbic acid and chlorine are mutually destructive: if one is present, then the other is not.

4. A KEY point of stain control is identifying the SOURCE of the problem. In many cases, you are simply wasting time and money if you don't first find the source of the problem.

Good luck!

(registration updated!)

[Nelsonto]

Thank you for your response! I have ordered the testing kits and will do my best to learn how to use them correctly. :-)

[JimK]

I have a 10K fiberglass pool that has iron stains. Although Ascorbic acid works great it makes it difficult to manage the chlorine levels (even with the Hayward SWG). I want to try the stain removal process described in the sticky on the forum but it mentions using Jacks Magic Pink Stuff. After I ordered that I noticed printed on the back of the bottle it states that for salt water pools Jacks Magic Purple Stuff should be used. Is that correct?

I've wondered the same thing. I've been using Jack's Magic Purple stuff for my salt pool (it's worked very well for me), but I wonder if using the Pink Stuff would be more economical since it's more concentrated (I can add smaller doses).

I've tried to find out what's different about the Purple Stuff (other than concentration) that makes it more suitable for salt pools, but no luck.

Interestingly, my pool passes the bucket test for metals (no discoloration whatsoever), but my steps will gradually start to stain if I don't use the Purple Stuff. Another interesting point is the stain only starts to appear when running the SWCG (I've never noticed any staining when shocking the pool in the spring using plain bleach). I was told by the company that installed my pool that the staining is from the small amount of impurities in the salt that gets released when running through the salt cell (there is a return in the steps; perhaps this is why it shows stains first?).

Perhaps next year I might try the CuLator.

[Poolsean]

"I was told by the company that installed my pool that the staining is from the small amount of impurities in the salt that gets released when running through the salt cell (there is a return in the steps; perhaps this is why it shows stains first?)."
This is not true or you would see it ALL the time. Do you have a gas heater? If it's metal staining, the metal has to come from somewhere. There's not enough metal in salt to cause staining, unless it's a granular salt that contains YPS (Yellow Prussiate of Soda), and is allowed to just sit on the pool finish without being stirred around to dissolve. Otherwise, salt is pretty benign, unless you add too much.
The Jack's Magic line of products are stain preventatives. I think you need to look at Sequestering agents, or metal removers, instead of preventative solutions. Getting it out of the water would be better than keeping it suspended, but still there.

[JimK]

We don't have a heater for the pool.

The only potential sources of metal I can think of are the salt and/or the city water used to occasionally top off the pool (I don't have to do that much since we usually get enough rain throughout the season).

What puzzles me is the fact that the bucket test shows no signs of metals present in the pool. What also is puzzling is that stains only start to appear when running the SWCG (Aqua Rite with T15 cell). I understand high chlorine levels can cause metals to fall out of suspension and attach to surfaces, but I've never noticed the start of any staining when shocking with just plain bleach (levels up to 30ppm+, with CYA level at 80ppm or less).

You mentioned looking at sequestering agents. I thought that's exactly what products like Jack's Magic are; ie they hold metals in suspension, preventing them from attaching to the pool surfaces. Am I misunderstanding this?

I've considered trying the CuLator, but from what I've read here it's still hadn't been proven to be effective. Also, it seems that it's slow to work (if it does work) requiring the use of a product like Jack's Magic to prevent staining in the meantime. And if metals are coming from our city water, then I would have to continue to use Jack's Magic until the CuLator removes the added metals.

This sounds like a pain to keep up with (having to constantly monitor for stains to determine when I can stop adding Jack's Magic and cleaning skimmer sockets to prevent the CuLator from gumming up). It also adds expense having to use both products (CuLator is not cheap).

Right now I just add a small weekly maintenance dose of Jack's Magic and don't have to worry about stains. Ideal? No. But it works for my pool.

I'm certainly open to ideas that would work and save money, but I'm not willing to risk having to deal with a stained pool again. I went through that once years ago, and once was enough (a PITA and expensive!).

[SunnyOptimism]

The company that makes the CuLator bags will also do water testing for you (for a nice fee, of course!). They will test both your fill water and your pool water if you send them samples and e-mail you a report. You could also buy a Taylor test kit for metals but they are kind of expensive and, at least for the Fe test, you need to know your ballpark concentration so you purchase the correct test kit.

This is my understanding of metal staining -

Ascorbic Acid (AA) - dissolves metal oxides that have come out of solution (due to high pH, high FC and/or both) and puts them back into your water as metal ions (a very long a expensive process but sometimes necessary).

Sequestrant - a metal complexing (or "chelating") agent (HEDP, EDTA, etc) that binds itself to a metal ion. The metal ions and chelating compound do not typically form a strong chemical bond and so it is possible that metal ions can stain as the sequestrant breaks down thus requiring constant additions of sequestrant on a regular basis to maintain a concentration that is adequate for keeping metal ions in solution.

Ion-exchange Resin (CuLator) - In "theory" the polymeric material in the CuLator bag acts a lot like the ion exchange resin in a home water softener. But, instead of calcium ions replacing sodium ions in the polymer resin and being bound there, the CuLator resin "binds" various different metal ions to itself. You can think of it like a localized sequestrant that you stick in your skimmer or filter basket.

The reason why I believe the CuLator is not very effective is because of a simple physical principle - if the the exchange resin is localized inside a bag you float in your skimmer, then practically speaking most of the water in your pool will flow around the bag and never come in contact with the resin. Sure you'll have diffusion of metal ions into the bag and given a high enough turn-over rate for your water you might bring more of it in contact with the bag, but that process will be very slow at best. The only way to make the CuLator resin material work in any meaningful way would be to build into an inline filtration system where ALL of your pool water is forced to flow through the CuLator material much like how a household water softener works. That, however, would require a very expensive setup almost akin to adding another "filter" unit to your pool plumbing.

Ultimately, if you have a high enough metal concentration in your pool water, your only options are - (1) use a regular dose of sequestrant to keep the metal ions in solution, OR (2) dump your pool water and refill with metal-free water and ensure that any auto-fill water source is free of metals. Once the swim season comes to a close here in my pool, I'll be spending the winter months looking at some minor stains on my plaster to see if metals are an issue...I really hope not because I'd hate to have to go through an AA treatment process and then be a regular Jack's Metal Magic user....

[JimK]

I have the same understanding as you. Having been through the AA stain removal treatment before, I don't want to do it again.

If it's not the salt that's adding metals to my pool, then it has to be our city water (despite the post from Sean {no offense Sean })I still suspect the salt/SWCG system since it's only an issue when running the SWCG). There's no equipment or anything else that I put in the pool that would be adding metals (thanks to the methods taught here, there's not much I have to add to the pool ). And since city water is the only source of water I have to top off the pool when we don't get enough rain for awhile (not often), I'm stuck dealing with it.

It's been reported here that Jack's Magic Pink Stuff is more concentrated than the Purple Stuff I've been using, so I may give that a try so I can use smaller doses/use less. However, I'd still like to know what is it about the Purple Stuff that makes it more suitable for salt pools, or is it just marketing BS?

PS - I find it interesting that a couple of coworkers of mine who use the same SWCG system (one has a vinyl liner IG pool, the other a fiberglass IG pool; we are all on the same city water system) have the same issue I have.

[SunnyOptimism]

I have the same understanding as you. Having been through the AA stain removal treatment before, I don't want to do it again.

If it's not the salt that's adding metals to my pool, then it has to be our city water (despite the post from Sean {no offense Sean })I still suspect the salt/SWCG system since it's only an issue when running the SWCG). There's no equipment or anything else that I put in the pool that would be adding metals (thanks to the methods taught here, there's not much I have to add to the pool ). And since city water is the only source of water I have to top off the pool when we don't get enough rain for awhile (not often), I'm stuck dealing with it.

It's been reported here that Jack's Magic Pink Stuff is more concentrated than the Purple Stuff I've been using, so I may give that a try so I can use smaller doses/use less. However, I'd still like to know what is it about the Purple Stuff that makes it more suitable for salt pools, or is it just marketing BS?

Yeah, I doubt it's from the salt. As long as you're buying salt meant for pool use and not some random water softener grade salt, it should be fine.

Two thoughts -

#1 - It is not at all implausible that your SWCG could be a culprit. The water chemistry environment INSIDE the cell when it is generating is very, very fdifferent than the bluk pool water. The pH is generally higher because of the chlorine production (rising pH) and the alkalinity is very low due to CO2 outgassing. So, if the water has metals in it, it is possible that your cell's chemical environment is causing the metal to scale out of solution and then it is being deposited wherever the returns are.

#2 - Have you checked your cell recently? It is always a good idea to check your cell's anode & cathode plates (as best as possible) to ensure that the precious metal coating (some mixture of titanium, platinum and rhodium) is not chipped, scratched or damaged. The underlying plate surface is likely either copper or stainless steel (copper be more likely) and you would definitely NOT want that exposed during cell operation.

#3 - Can you get water quality reports from your municipal water supplier? Typically the EPA requires that all municipalities test their water supplies and provide report data for all metals. Alternatively, you could try to bucket test your supply water to see if it scales out metals.

Just some thoughts...

[JimK]

Thanks for your feedback.

Yes, I do inspect the cell periodically. No problems there.

As I mentioned, the stains first appear on the steps. There is a return in the steps and the steps are white, which is probably why I notice it there first.

I'll see if I can find water quality info on our city water.

I take it a passing bucket test for metals doesn't necessarily mean the water has no metals, perhaps just a low level of metals? When I did the bucket test there was absolutely no staining/discoloration in the bucket.

I do stick with "pool salt" that says "no additives". I do not use water softener salt.