Weird cement leaking into pool - Is it dangerous to swim?

[danobrien]

After opening my pool I noticed some very strange stains. Last year the cracks in between the stones around the pool was repaired, but I noticed the cement had turned soft and I suspect was leaking into the pool. I believe the cement was the cause of the staining. I posted another thread about this. Jack's magic tested positive for Copper And Scale. SInce it is not copper I assumed it is scale. I used the stain treatment and it worked. However, the stain is reappearing now. It may just be a resettling or maybe the cement is continuing to leak into the pool. I'm not sure but I suspect the latter. I've removed the cement now, so hopefully further staining will not occur.

If the cement is in the pool, could be possible be dangerous to swim? Is there a way to tell? Unfortunately, I do not know what cement was used and I have no way to tell. I do have the cement pieces but not the original container. Whatever was used was not good because it did not dry properly.

Should I be concerned?

 

[mknauss]

Can you post a picture of what you are seeing?
It would not be 'cement' per se. It could be efflorescence, or scale.

Your Poolmath log you have shared only shows a couple bleach additions. If you enter your test results into the App we can see those. The test results will show you if it is safe to swim.

 

[danobrien]

All my numbers are good. The question I am asking here is whether, assuming that the something from the cement leaked into the pool, could it be harmful (if swallowed for example). What if the cement has harmful chemicals in it? Keep in mind that whatever they used may not have been regular cement because otherwise it would not have turned to mush. For example, what if they used grout with coloring or something like that. The cementing was not done by a professional.

Not sure it is relevant but, I posted a previous picture and have a previous thread about it: Unusual Stains in Pool There is an error however in that I subsequently found out my pool is gunite, not fiberglass. Also the original stains went away after treatment with Jacks magic, however, some of the staining started to reoccur. It's not nearly as bad as it was.

Here are my readings:
Alkalinity 89
PH: 7.4
CH : 225
TC: See note below.
CYA: 30

Note: As per information from Jacks magic I cannot test for free chlorine now. They said the CC reading will be the Total Chlorine. I mistakenly thought the new staining was algae so I shocked the pool, but subsequently realized the staining is not algae. I test for the chlorine as follows:
1. Add the R-0870 powder
2. one drop of R-0871 and it turns clear
3. Add 5 drops of R-0003- turns very pink
4. Now I add drops of R-0871. Now it gets strange. After adding 15 drops the solution turns and stays clear for a couple seconds, then I add another 5 and it turns clear again for longer but then turns pink again. It seems that I can keep adding drop and if I let it swirl long enough it turns pink again. If I let it swirl long enough it seems to always turn to pink. So I'm not sure what reading to use. When I use another Total Chlorine test it reports above 5.0.

 

[mknauss]

Sounds like you have a lot going on chemically.

The picture in the other thread shows what is in the pool I assume. Can you show a picture of where it is coming from?

 

[danobrien]

Three pictures below.
The first shows the removed cement. In some areas the cement was mushy rather then soft solid.
The second shows one of the cracks after I removed the cement.
The third shows the stones around the pool.

 

[ajw22]

If the cement is in the pool, could be possible be dangerous to swim? Is there a way to tell? Unfortunately, I do not know what cement was used and I have no way to tell. I do have the cement pieces but not the original container. Whatever was used was not good because it did not dry properly.

Should I be concerned?

You call it cement so let's talk about cement. Here are the ingredients in cement - 8 Main Cement Ingredients & Their Functions - Civil Engineering

Ingredient	Percentage in cement
Lime	60-65
Silica	17-25
Alumina	3-8
Magnesia	1-3
Iron oxide	0.5-6
Calcium Sulfate	0.1-0.5
Sulfur Trioxide	1-3
Alkaline	0-1

Nothing there is inherently dangerous especially when diluted in your pool water.

We don't know if other chemicals were added in by the non-professional who mixed it.

What was used may have been mortar or grout that is other mixes of cement with sand and lime.

@MinerJason may have some thoughts.

 

[danobrien]

You call it cement so let's talk about cement. Here are the ingredients in cement - 8 Main Cement Ingredients & Their Functions - Civil Engineering

​

Ingredient	Percentage in cement
Lime	60-65
Silica	17-25
Alumina	3-8
Magnesia	1-3
Iron oxide	0.5-6
Calcium Sulfate	0.1-0.5
Sulfur Trioxide	1-3
Alkaline	0-1

Nothing there is inherently dangerous especially when diluted in your pool water.

We don't know if other chemicals were added in by the non-professional who mixed it.

What was used may have been mortar or grout that is other mixes of cement with sand and lime.

@MinerJason may have some thoughts.

Thanks! That is very helpful. Whatever they used, they did not add anything unusual to the cement.

 

[MinerJason]

Cement is an ingredient in mortar and concrete, and whatever was used there was not just cement, though it may have had a small amount of cement in it. Since you state that they didn't add anything unusual to it, I'm guessing it was some sort of pre-blended bagged product that was mixed with water and then applied. Based on the fact that it's very soft and disintegrating where it came in contact with water, my guess would be that a low quality thinset mortar was used, which is completely the wrong material for this application. A standard mortar mix (not a thinset) would be the appropriate thing to use here. Was this same material used beneath the coping as well, or just between the joints?

 

[danobrien]

Cement is an ingredient in mortar and concrete, and whatever was used there was not just cement, though it may have had a small amount of cement in it. Since you state that they didn't add anything unusual to it, I'm guessing it was some sort of pre-blended bagged product that was mixed with water and then applied. Based on the fact that it's very soft and disintegrating where it came in contact with water, my guess would be that a low quality thinset mortar was used, which is completely the wrong material for this application. A standard mortar mix (not a thinset) would be the appropriate thing to use here. Was this same material used beneath the coping as well, or just between the joints?

It was just used between the joints. From what I saw, the powdered material was from a bag and they just added water to it. Would you agree that it is probably not anything inherently dangerous?

 

[MinerJason]

It was just used between the joints. From what I saw, the powdered material was from a bag and they just added water to it. Would you agree that it is probably not anything inherently dangerous?

Yes, very unlikely there's anything dangerous to your pool in whatever that was, particularly in the small quantities that got into the water.