Redish Brown Stain on Bottom

[GriffithJerryl]

Last year I noticed a stain developing on bottom along one side roughly 12 to 18 inches wide running most of the length of the pool and stops about 4 to 5 ft from ends. This year I noticed the stain has grown in middle deep part of the pool about 6 to 8 ft wide. It is not a solid, uniform appearance and actually has some "clean" trails winding through it. It does not brush off with vigorous effort multiple times. I thought maybe it was Yellow Algae so I used a product called Yellow Gone following the directs of brushing and adding two pounds of shock five minutes later. No improvement.

Two or three years ago I noticed a tiny rust looking stain on one wall about five inches up that produced a stain trail starting with the tiny spot and running down the wall for few inches and gets widens to about half inch. I bought a product call Stain Spot Treat Spotting Bag with Oxalic Acid. Following the directions of turning off the pump and placing the bag on the large stain area near the side of the pool at about 4 ft dept. Put a brush on top of it to hold it down per instructions on the package. Next morning a spot was perfectly clean (white) the size of the bag plus a "clean trail" running from the bag placement spot toward the deeper center. The dissolved product in the bag was heavier than the surrounding water and made the clean trail starting the size of the little 3" x 5" bag getting ever wider is the dissolved product ran down the slope toward the deepest part of the pool cleaning the stain off. I am on city of Little Rock Water and it is fairly soft water and does not have much dissolved solids.

I keep the pool open year around by using a leaf net plus monitoring and maintaining the chemical balance. The water has been perfectly clear for 8 years since new and never had any discoloration of the water or plaster surface from algae of anything else until last couple of years when stain started appearing. Sometime near end of year one I started using the Prestiva Salt $40 a bag plus the Prestiva quarterly additive until the compressor went out on my heat pump two weeks before 5 year warranty expired but it still cost me $1,000 labor and R410A gas. I bought all of my pool supplies, $40 a bag salt and heat pump form a pool builder and supply store but stopped doing business with them when I found out they sold me an obsolete AquaCal Heat Pump that burned me for $1,000 labor.

So three years ago I started using Diamond Crystal Splash Ready Pool Salt. I used that salt a little over two years. About a year ago when Lowe's store opened nearby I noticed they stocked the full line of Clorox Pool Supplies so i started using the Clorox Salt which claims a high degree of purity. I first noticed the stain a year or more before i started using the Clorox Salt. I called the AquaCal help line that I have used before on failure of the compressor and water temp sensor failure which was built into the Heat Exchanger and not serviceable. I asked if there was any chance that the Heat Pump could be putting out iron. They told me the material was titanium which would not rust.

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Has anyone ever noticed an issue with Diamond Crystal Pool Salt causing a stain buildup? The stain cleans off very well with that Stain Spot Treat product that contains Oxalic acid. It is just for spots but it works great on my larger stain. I need to drain the pool anyway and have it replastered or at least touched up because the jerk that did the plaster work had an attitude and plastered in organic stuff so once the skim coat of plaster eroded the organic trash eroded away leaving a dozen small "divots" from one to three inches wide and long with various degrees of light stain where the organic trash mixed with the plaster. I am preparing my home for sale and need to have those divots patched or entire pool replastered of the new plaster guy I am calling today gives me a price and references that meet my approval. Plus the single digit temps Winter 2017/2018 caused damage to some coping brick that soaked up some water that when it froze it exploded the coping brick. That looks like Crud and must be repaired.

Attached are some photos of the stain, yellow plastic and divots. I would definitely appreciate and help with my stain dilemma. Hope I can acid wash the stain and if the plaster guy thinks he can patch the dozen ugly spots for a reasonable price I will go that route. Wonder if using a diluted solution of Muriatic Acid can be used to clean it. The Stain is not dark so would not take a very strong solution of Muriatic Acid to clean the stain. One more question. I notice my pastice parts like old wheel on Polaris and water jets are extremely yellow. Those items are 8 years old.

Sport Pool 15 x 35 Depth 3' Ends 5' Center
8 years old unless otherwise noted
White Plaster
15,000 Gallons
Jandy ePump VSP
AquaCal Heat Pump Model 156ARDSBTC (Titanium Heat Exchanger)
Polaris 280 with Booster Pump
Salt Water Chlorine Generator Jandy Pro Series AquaPure PLC1400-25 (One Year Old)
Hayward ProSeries High Rate Sand Filter S24412

 

[Texas Splash]

Sounds like you may have a couple issues to contend with - a few plaster dimples/defects and minerals in the water - iron perhaps. Perhaps the first place we should start is ask how you test your water? Do you have a TF-100 or Taylor K-2006 test kit, and can you provide a full set of results? That would give us a good reference point. Now if those numbers raise no other questions, we might be inclined to believe that your pool picked-up some iron or copper along the way. Because the acid you used seemed to work, I'm leaning more towards iron. You might also test that theory by placing some Vitamin C tabs (crushed) in a thin sock or nylon and resting it on some of thsose discolored areas. Maybe even try it on the plastic wheels and such. If they turn white, you know it's iron. Then you can explose an ascorbic acid treatment. You would also have to investigate how iron got into the water. We've seen where some salt products contain excessive amount of contaminants, to include iron, so that's one area. Even some city water supplies have a slightly elevated iron content. Add that to lots of seasonal refills and the iron level just keeps building.

But I would start with a full set of water test results and try that Vitamin C test on some areas. Let us know what you find.

 

[YippeeSkippy]

I was leaning towards copper myself. You've added an assortment of chemicals over time that we don't recommend, so I wondered if you've ever added any copper containing algaecides? They're usually the cheaper ones on the market.

Maddie

 

[GriffithJerryl]

Thank you both for your help. I use the Taylor K-2006 and I use a speed stir. Is the TFTestKits TF-100 a better kit for more accurate results? Only "assortment of chemicals" i have ever added over time are the same ones required for all SWCG pools, salt, acid, alkilkinity, calcium hardness, cyanuric acid (stabilizer) except last week I experimented with the Yellow Gone for the first time ever and the Pool Stain Treat Spot Bag that has oxalic acid in it that removed the the stain. The little stain divots are nothing more than trash in the plaster left there by the jerk that did the plastering because was too lazy to clean the trash out. Only thing that can fix that is new plaster. I am inclined to believe that it is iron and the iron has come from the Diamond Crystal Pool Salt since it grew over the past couple of years. I never had any discoloration using the $40 a bag Prestiva Salt. Sounds like the vitamin C might be the ultimate test for iron since it will remove Iron stains but it won't tell me the source. Since was slow build up over past few years that really points to the Diamond Crystal Salt. Unless it is in the city of Little Rock, AR water and the Prestiva system eliminated the dissolved solids. I'll do a full water test tomorrow and post it here plus will test the vitamin C crushed tablets (without rosehip). I have not done any seasonal refills because I leave the pool open all year and keep it in balance all year. I have an automatic water makeup when it does not rain enough and in winter when i have to disconnect the auto makeup supply i add makeup water with water hose. With 71.4 inches of rain last year I didn't have to add much water and the auto makeup didn't run much. I have been 1,100 feet down into a Carey Salt Mine in Winfield Louisiana and have seen iron stains in the salt crystals. Of course different mines could have different contaminants.