Yellowish-brown Staining On Steps, Skimmers, Etc.

[chem geek]

Yes, if you remove the stain so that the metal is in the water and then you replace the water with fill water free in metals, then you won't need to continue to use metal sequestrant and shouldn't need to test for metal again.

Most likely the product a pool store had you add was an algaecide that had copper in it. I don't think there's any pool store product that adds iron. However, ascorbic acid usually removes iron stains best; it's citric acid that removes copper stains. So your experience is a little off though it's still possible you had a copper stain that was removed by your ascorbic acid treatment, especially since it was only on vinyl and not plaster.

[Charmaine]

Thank you so much for your reply. Honestly, most of the staining is on the stairs, ladders, skimmer etc. All things white are completely brown. The liner is only slightly affected. I expect my husband will drain and refill. So, if in fact it was an algaecide with copper, is there a brand that does not contain copper? And what product should we use an asorbic acid or citric acid? Based on the readings above and the Vit C test I thought asorbic acid...I'm sorry, I am now further confused. The Vit C tablet removed the stain instantly and has not returned in the area cleaned. Thanks again, Charmaine confused in Maryland!

[chem geek]

If you maintain an FC level that is appropriate for your CYA level, then you shouldn't need algaecide, clarifiers, flocculants, shocking, or any other products. Just chlorinating liquid or bleach (once other pool water chemistry parameters are in balance) and a small amount of acid. Read the Pool School for further info.

If you insist on using an algaecide because you want to use Trichlor tabs, then Polyquat 60 algaecide would be better, but needs to be added weekly. Another option is to use a phosphate remover but that can get expensive. The problem is continued use of Trichlor tabs as your sole source of chlorine. For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.

[Charmaine]

Great, thank you for the details. That really helps. What about the staining? Your recommendation is asorbic acid or citric acid? I'm guessing either??

[chem geek]

Since the ascorbic acid worked, you can use that to remove the stain. Then you need to decide what to do next. Use a metal sequestrant product (HEDP-based -- see some recommendations in the Pool School) both initially and with a weekly maintenance dose OR use a product like Metal Magic that tries to coagulate with the metal to get caught in the filter OR use CuLator in the skimmer to physically remove the metal from the water OR do water replacement to remove the metal. You'll need to compare costs of each approach to decide what's best since in some places water replacement is least expensive while in others the water is more expensive (or scarce).

[Charmaine]

Got it! Thanks again, wish us luck

[kolffan]

Hello,

This is a long post... follow-up question to Charmaine's entries regarding repeated orange/yellow pool wall staining (plus cloudy water), which we have been dealing with for several years of opening/closing pool for season changes. We are on well water, have had our water tested and been told minerals are normal, as well as ph, alkalinity, cyanuric acid. We have a 14k gallon inground fiberglass pool with paper cartridge filters (recommended by pool installer as we are on well water). The cartridge filters were just changed to new.

We've used Vitamin C stain remover successfully to remove yellow/brown stains from our fiberglass inground pool during low chlorine PPM, subsequently use sequestrant like Metal Free and retail Stain/Scale preventer after 24 hours of circulation, wait about 12 hours thereafter before chlorination. I used up to one bottle (20 oz or so) of sequestrant. I flush the paper filters. Chlorination is where the problem recurs.

We've tried 2 types of chlorine - powder calcium hypchlorite vs liquid sodium hypochlorite. Calcium hypochlorite doesn't seem to cause walls to restain (at least not immediately) and the water upon treatment doesn't turn green as does liquid sodium hypochlorite but doesn't clear the cloudy water. Liquid sodium hypochlorite immediately has the water greenish tint, and within an hour or so the walls restain significantly virtually back to original discoloration. The walls are so stained that I can't tell if the pool water's green tint dissipates over a day or two while pump runs. (Our fiberglass pool's wall are very light blue color.)

Here's a second factor that I've been told may be contributing to the cloudy water/staining. For a few years after pool was originally installed, we used pool winterizing liquid (antifreeze) in the lines with no problems. For about 6 years or so recently, we've been using RV antifreeze, which is non-toxic and I read on-line it is possible to do so. However, what a pool store told me is the RV antifreeze does not dissipate over time as does pool winterizing antifreeze and concentration builds up season to season. They called the antifreeze manufacturer, and there is no retail/commercial water test to determine the RV antifreeze concentration. A formal lab sample test costs about $600 and weeks for off-site results. The high concentration of antifreeze apparently is bonding with chlorine and causes very high consumption chlorine (which I've noticed that chlorine is consumed very quickly, within 1-2 days), and also the cyanuric acid doesn't retain the chlorine as it's depleted a lot faster because of the RV antifreeze. The RV antifreeze may also be causing cloudy water and promoting wall staining. The pool service company said the pools they maintain each season they found this RV antifreeze, and once they stopped using it and reverted to regular pool antifreeze, they had no problems with cloudy water/wall staining subsequent seasons. But if the RV antifreeze concentration is high, the contaminated water needs to be replaced with fresh water.

So please advise why the two different types of chlorine have different effect on wall staining and reducing water cloudiness. Also, short of replacing all the water after using vitamin C to remove stains, why the use of sequestrant and stabilizer doesn't prevent the liquid chlorine to cause immediate wall re-staining.

Thanks for any help you can provide.

[kolffan]

Local pool service uncertain why calcium chloride doesn't immediately cause fiberglass pool wall staining whereas sodium chloride does. However, they are not calcium chloride proponents because it causes calcium deposits on surfaces (tan spots as opposed to entire surface stained), but downside of sodium chloride is salt buildup, which at high levels (3,000 ppm) can promote corrosion. They did state though that salt chlorinators have 1-2k ppm salt but at that level doesn't seem to be a concern. The pool service company said after the stains are removed and chlorination resumes, that normal dosage of chlorine should occur, shocking shouldn't be necessary (read further about this chlorination).

The pool service company still says the most reliable solution is a full water drain and fill. They calculated if partial water removed (not full) it would take 30+ cycles to achieve similar end result. I did about 4 cycles of partial drain (10-15% each time) before the prior stain removal/chlorination and it seemed to help... until the sodium chloride incident described in my prior post.

A different post on this website stated that after using the vitamin c & sequester that low amounts of chlorine added over several days is recommended (i.e,. not an immediate pool shock) so that chemical balance can remain the same, not a drastic change. I am trying this approach the next few days. This time I'm using the same manufacturer for both the vitamin C and sequestering agent (Natural Chemistry Stain Free & Metal Free). The Stain Free instructions are to dispense the contents, brush the pool walls and after an hour add the Metal Free. No chlorine for about 2-3 days. Then I plan to add the chlorine in smaller amounts. It could be that I've added too high chlorine in the initial application (7-8ppm) and that resulted in oxidation and immediate wall staining.

Thoughts?

[kolffan]

Local pool service uncertain why calcium hypochlorite doesn't immediately cause fiberglass pool wall staining whereas sodium hypochlorite does. However, they are not calcium hypochlorite proponents because it causes calcium deposits on surfaces (tan spots as opposed to entire surface stained), but downside of sodium hypochlorite is salt buildup, which at high levels (3,000 ppm) can promote corrosion. They did state though that salt chlorinators have 1-2k ppm salt but at that level doesn't seem to be a concern. The pool service company said after the stains are removed and chlorination resumes, that normal dosage of chlorine should occur, shocking shouldn't be necessary (read further about this chlorination).

The pool service company still says the most reliable solution is a full water drain and fill. They calculated if partial water removed (not full) it would take 30+ cycles to achieve similar end result. I did about 4 cycles of partial drain (10-15% each time) before the prior stain removal/chlorination and it seemed to help... until the sodium hypo-chloride incident described in my prior post.

A different post on this website stated that after using the vitamin c & sequester that low amounts of chlorine added over several days is recommended (i.e,. not an immediate pool shock) so that chemical balance can remain the same, not a drastic change. I am trying this approach the next few days. This time I'm using the same manufacturer for both the vitamin C and sequestering agent (Natural Chemistry Stain Free & Metal Free). The Stain Free instructions are to dispense the contents, brush the pool walls and after an hour add the Metal Free. No chlorine for about 2-3 days. Then I plan to add the chlorine in smaller amounts. It could be that I've added too high chlorine in the initial application (7-8ppm) and that resulted in oxidation and immediate wall staining.

Thoughts?

[chem geek]

As shown in this MSDS, swimming pool antifreeze is propylene glycol and it is the same as in SOME RV antifreeze. The problem is that some RV antifreeze contains other chemicals such as shown in this MSDS that also lists glycerol or this MSDS that also lists ethanol (though that should not be a problem).

Regardless of whether you use RV antifreeze or swimming pool antifreeze, having propylene glycol added to the pool water will create a chlorine demand. You should not be dumping the anti-freeze from your lines into the pool. In suction lines you should evacuate them to waste rather than recirculate. For returns, you should drain them one at a time into a bucket or otherwise prevent most of it from getting into the pool. See this thread where I had labs to water tests on two pools that showed unusually high chlorine demand and it seems to indicate that unlike what the pool store claims, the anti-freeze does NOT build up but rather what is going on is that the propylene glycol gets oxidized by chlorine, possibly to hydroxyacetone and maybe to chloroform but that these latter two outgas from the pool. However, this should have little to do with any staining.

As for your other water balance questions and metal staining, I suggest you read the Pool School.

[MoroccanBath Addict]

Thanks guys, I have the same problem and finally it's over now. This forum is so helpful!