Brown stains in tiled salt water pool!?!

[Wobiwan]

Well, first time poster... go easy. Hope this is the right thread. So here is goes:

We have a 45qm salt water pool, its in Northern Spain, and is operating all year round. The pool is tiled and has had a full re-tile 10 months ago. At that time it was also changed from chlorinated to saltwater using an automated system. The water is filtered around 8 hrs a day, every day. The pool is cleaned every 3 weeks on average, more often in summer. Water is crystal clear, and no algae seems to be present. The walls are brushed every 4-6 weeks, which results in some milky substance being brushed off (salt deposits?)

5 months ago, after being absent for 3 months before that, I noticed that we seem to have some built up of a brown substance on the grouting between the tiles. SInce these are new tiles an new grouting, I was a bit suprised, as it also appeared in patches.

It wa possible to fairly easily brush it off, but a week later it was back. Not always in the same spots, but all over the pool, walls, bottom, steps... anywhere really. The pool company that did the renovation and tiling was at a loss. They suggested I try some anti algae, but that did help.

Now I had the water tested and the results point to high chlorine levels and some high Manganese levels. Any thoughts on where to go from here??

 

[PoolStored]

Welcome to TFP!!!

One of the first foundations of TFP is to do your own testing. Pool water testing can be inaccurate. The Taylor K-2006C-Salt-Complete is available in Spain. The source for Spain are the following: BEHQ SL (34-93-846-53-36) or [email protected]. I would reach out and get a kit ordered today.

The walls are brushed every 4-6 weeks, which results in some milky substance being brushed off (salt deposits?)

We recommend brushing weekly.

While I don't necessarily believe the pool store test, your CSI is very negative at -1.7 (with pool water temperature of 75F). CSI that is very negative is corrosive to plaster and grout, which could be the cause of the milky substance.. Do you know what type of grout was used?

Your TA an pH are very low, which is the cause of the low CSI. I would add 30ppm of baking soda to the pool. Normally, we don't make recommendations based on pool store testing, as we can do more harm than good. In this situation, adding 30ppm will NOT damage the pool, and would likely help step the damage to the grout.

Do you know the volume of your pool? Post that and we can help with how much baking soda will raise the TA by 30ppm.

Algae can appear brown. Others will chime in, but until we have good water test results, it will be hard to know any other good next steps.

1. Order the test kit.
2. Figure out the grout type.
3. Brush weekly.
4. Post the volume of the pool and we'll help you with how much baking soda to add.
5. When the kit arrives, post a full set of results...FC, CC, pH, TA, CH, CYA, Salt.

 

[ajw22]

Welcome to TFP.

You have algae. Yes, you can have algae with a perfectly clear pool. The algae is showing on your grout and on your tiles when you brush the pool.

Your water chemistry is not good. Your pH is low, Ta is low, chlorine is low, and I don't know if you have CYA in the water.

Brushing every 4 to 6 weeks is not adequate. Pools need to be brushed every few days and at least weekly to break up the biofilm that protects algae from chlorine.

I suggest you read our Pool School and

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!

www.troublefreepool.com

Algae Archives

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TFP Pool Care Methods start with having your own test kit and doing your own water testing. Getting a good test kit can be difficult in the EU.

Read about TFP Pool Care Methods and see what you want to follow. But basically your pool needs more chlorine and care.

 

[Wobiwan]

One of the first foundations of TFP is to do your own testing. Pool water testing can be inaccurate. The Taylor K-2006C-Salt-Complete is available in Spain. The source for Spain are the following: BEHQ SL (34-93-846-53-36) or [email protected]. I would reach out and get a kit ordered today.

Well, thats the exact company did the lab test. It wasnt tested in a store. So I have no reason not to trust (or believe) the results.

your CSI is very negative at -1.7 (with pool water temperature of 75F). CSI that is very negative is corrosive to plaster and grout, which could be the cause of the milky substance.. Do you know what type of grout was used?

Excuse my ignorance please (perhaps lost in translation), but what CSI are you referring to? What is CSI? I dont see any value of -1.7. I will ask about the grouting, that will be useful to know.

You have algae. Yes, you can have algae with a perfectly clear pool. The algae is showing on your grout and on your tiles when you brush the pool.
Your water chemistry is not good. Your pH is low, Ta is low, chlorine is low, and I don't know if you have CYA in the water.

Chlorine seems very high, if I read the test correctly both Cloro Libro [ free chlorine] and Cloro Combinado [Combined Chlorine] are above 15 compared to a average of less than 0.5. Why would you think its low if I may ask? As mentioned, we applied a anti-algae treatment (two applications a few weeks back) but it made no difference. Just tying to understand it, not arguing with you ;-)

Brushing every 4 to 6 weeks is not adequate. Pools need to be brushed every few days and at least weekly to break up the biofilm that protects algae from chlorine.
I suggest you read our Pool School and

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!

www.troublefreepool.com

Algae Archives

www.troublefreepool.com

yes, I agree, brushing needs to be increased.

 

[PoolStored]

Well, thats the exact company did the lab test. It wasnt tested in a store. So I have no reason not to trust (or believe) the results.

Soooo, a couple things.

1. Water degrades when you take it out of the pool and send or take to a lab.
2. Don't confuse precision (ph =6,83) with accuracy. They are using electronic testing. Drop testing at home is more accurate. Providing advice to you without accurate testing, we could do more harm. Order the kit.

Testing_Accuracy.jpeg

• PoolStored
• Sep 16, 2024

Excuse my ignorance please (perhaps lost in translation), but what CSI are you referring to? What is CSI? I dont see any value of -1.7. I will ask about the grouting, that will be useful to know.

CSI is a measure of pool water being corrosive (will etch plaster/grout) when negative, or be inclined to scale when positive. CSI can be calculated by pool math. Link-->PoolMath

With a negative CSI, it can be corroding the grout.

CSI and LSI - Further Reading

www.troublefreepool.com

Chlorine seems very high, if I read the test correctly both Cloro Libro [ free chlorine] and Cloro Combinado [Combined Chlorine] are above 15 compared to a average of less than 0.5. Why would you think its low if I may ask? As mentioned, we applied a anti-algae treatment (two applications a few weeks back) but it made no difference. Just tying to understand it, not arguing with you ;-)

I said your pH is low and your TA (alcalinidad) is low. Low TA typically leads to low pH. Low pH and low TA will drive CSI negative and likely the cause of your white clouds when scrubbing.

 

[Wobiwan]

Thanks, I am learning a lot here. The water went to analysis the next day, in a sealed bottle. But yes, I see your point. And it was 'ajw22' not you, that mentioned low Chlorine levels. I am waiting to hear back from the Pool company, about the grouting, and will post here when I know it.

As mentioned in my OP, the pool is 45qm in size. I am hoping to have the pool company do the test here, as I am a little surprised to the cost of the test kit... over 200 USD here! If they have one, then I dont need to buy it.

 

[ajw22]

And it was 'ajw22' not you, that mentioned low Chlorine levels.

Yeah, I was looking at the wrong column in trying to translate the test.

Even chlorine > 15ppm can be too low depending on your CYA levels.

Read...

What Are My Ideal Pool Levels?

Use our tool to find ideal chemical levels for any swimming pool. Check TFP recommended levels on pH, free chlorine, cyanuric acid, and more.

www.troublefreepool.com

and I will leave it to you to compare your water chemistry to TFP recommended levels.

If they have one, then I dont need to buy it.

We recommend you do all your own testing for consistency and repeatability.

I don't know how much you spend for your pool care and chemicals but $200 for a test kit should be a minor pool expense.

You should do a Overnight Chlorine Loss Test to see if your pool has algae. If you fail the test then you need to follow our SLAM Process. To follow TFP Methods like that you need to be doing your own testing during the processes.

 

[PoolStored]

The water went to analysis the next day, in a sealed bottle. But yes, I see your point.

We recommend you test your water right away. The longer the sample is out of the pool, the more that FC and pH are off...

the pool is 45qm in size

We don't understand what qm means. Do you have the pool volume in litres?

 

[Wobiwan]

qm = qubic meter. 1qm = 1000l (my bad... thinking with my foreign brain. (It should be 'cubic meter' but cm always refers to centimeter where I am from)

 

[PoolStored]

I’d add 2.2kg of baking soda (sodium bicarbonate) to raise TA.

 

[Wobiwan]

...Apart from the test kit, I think i will have to find a reliable pool company for maintenance, as we are likely away again for some months. In the meantime there is a different problem. Torrential downpour washed a lot of the substrate that was used on the lawn into the pool ;-)

 

[ajw22]

Torrential downpour washed a lot of the substrate that was used on the lawn into the pool ;-)

What type and model filter do you have?

What type and model pool cleaner do you have?

It is helpful to us if you put all that information in your signature. See Create Your Signature - Further Reading

Filtering 24/7 + pool cleaner + maybe SLAM Process will clear your pool over time.

Precautions and Procedures During Floods - Further Reading

www.troublefreepool.com

 

[Wobiwan]

Thanks, I have already cleaned up most of it. Water still a little murky, but its more or less back to what it was. Need to keep running the filter.

We have a AstraPool Sandfilter (using glass instead of sand I believe). Pool cleaner? I just sucked up the soil on the floor to waste. Now backwashing and rinsing daily, to ensure the filter is not getting clogged. BTW< I did put that info into the profile, but seems to not stick.. huh

 

[mknauss]

I did put that info into the profile, but seems to not stick.. huh

Create Your Signature - Further Reading

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[ajw22]

. BTW< I did put that info into the profile, but seems to not stick.. huh

Profile and Signature are two different areas…

Create Your Signature - Further Reading

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