Ok so.....this is where i'm at. A customer called us a week ago to close a pool. I checked the levels in the pool and the PH was below 6, ALK was 0. They had been using HTH trichlor tabs for at least this season. Also i'm pretty sure they never adjusted PH.....or checked it. So over the last week I raised the ALK to 100 PH to 7.6. Now upon returning to the pool over the weekend the water has turned blue and blue flecks are precipitating out of the water. This is to the point it will stain....if I dont let it collect in the filter. ......now I have seen this once before, after being called when the pool turned blue. Now both of these have 2 things in common, they both used HTH and they both had thier PH adjusted drastically over a few days (using soda ash, and sodium bicarb for ALK). Does anyone have any experience with this? I believe it is a chemical reaction between the PH and the clarifier that's included in the HTH.
Low TA and ALK adjusted to normal levels lead to blue pool
- Thread starter PJ
- Start date
y_not
0
Re: Low TA and ALK adjusted to normal levels lead to blue po
GOSH!!! One more reason to stay the hay away from Walnasty!!
Could it be the copper that is in those tablets? I know copper goes green, not blue in the presence of CL. But is it possible for it to go blue against maybe a blue liner or pool surface?
Highly, highly oxidized copper out in the elements is almost blue in the right, low Kelvin lighting. That green + almost blue hue really leans more toward the blue hue.
Say at dawn with an overcast sky possibly.
Lastly, copper sulfate is a ROCKIN' blue!
PS. Do you have a picture? Pretty please??
GOSH!!! One more reason to stay the hay away from Walnasty!!
Could it be the copper that is in those tablets? I know copper goes green, not blue in the presence of CL. But is it possible for it to go blue against maybe a blue liner or pool surface?
Highly, highly oxidized copper out in the elements is almost blue in the right, low Kelvin lighting. That green + almost blue hue really leans more toward the blue hue.
Say at dawn with an overcast sky possibly.
Lastly, copper sulfate is a ROCKIN' blue!
PS. Do you have a picture? Pretty please??
Re: Low TA and ALK adjusted to normal levels lead to blue po
It's probably copper. What more can you tell us about the pool?
How were the tabs added (skimmer, feeder etc)?
Is there a heater?
What material is the pool (vinyl, fiberglass, plaster etc)?
What are the calcium and the cyanuric acid levels?
Can you test for copper?
It's probably copper. What more can you tell us about the pool?
How were the tabs added (skimmer, feeder etc)?
Is there a heater?
What material is the pool (vinyl, fiberglass, plaster etc)?
What are the calcium and the cyanuric acid levels?
Can you test for copper?
Re: Low TA and ALK adjusted to normal levels lead to blue po
http://s1356.photobucket.com/albums/q72 ... oolandspa/
There ia a link to some pics...(I can't figure out how to post directly.)
It is a vynil lined pool, only a couple of years old,and it has a heater.
CAL 300
CYA 50
http://s1356.photobucket.com/albums/q72 ... oolandspa/
There ia a link to some pics...(I can't figure out how to post directly.)
It is a vynil lined pool, only a couple of years old,and it has a heater.
CAL 300
CYA 50
- Jun 20, 2012
- 439
Re: Low TA and ALK adjusted to normal levels lead to blue po
I suspect the precipitation is from the heater.
Will it brush loose and vacuum out to waste?
I would suggest adding a sequestrant, for insurance.
In the future, whenever trying to bring a pool back from a low pH, low alkalinity condition, add a sequestrant and leave the pool running 24/7.
PJ said:
I suspect the precipitation is from the heater.
Will it brush loose and vacuum out to waste?
I would suggest adding a sequestrant, for insurance.
In the future, whenever trying to bring a pool back from a low pH, low alkalinity condition, add a sequestrant and leave the pool running 24/7.
Re: Low TA and ALK adjusted to normal levels lead to blue po
Yes it does come loose and vacuum to waste. The filter is getting most of it. Why did it all of the sudden turn blue when we got it balanced and not before?
Yes it does come loose and vacuum to waste. The filter is getting most of it. Why did it all of the sudden turn blue when we got it balanced and not before?
- Jun 20, 2012
- 439
Re: Low TA and ALK adjusted to normal levels lead to blue po
My guess is that there's a huge amount of copper in the water (you'll probably be selling them a new heater soon). I suspect that the water is pretty hard (high calcium hardness). When you aggressively increased the pH and alkalinity the result was a solid precipitate. I would like to see some other comments on this.
PJ said:
My guess is that there's a huge amount of copper in the water (you'll probably be selling them a new heater soon). I suspect that the water is pretty hard (high calcium hardness). When you aggressively increased the pH and alkalinity the result was a solid precipitate. I would like to see some other comments on this.
Re: Low TA and ALK adjusted to normal levels lead to blue po
I guess what I will do is get most of it out and put in a sequestering agent for the winter just to be safe.
I guess what I will do is get most of it out and put in a sequestering agent for the winter just to be safe.
Re: Low TA and ALK adjusted to normal levels lead to blue po
See copper carbonate which is a blue-green color and would form from a high TA and pH combination since that increases carbonate levels substantially. See copper hydroxide as well and is pale blue though this forms from high pH independent of the TA level. It's copper oxide that is darker.
See copper carbonate which is a blue-green color and would form from a high TA and pH combination since that increases carbonate levels substantially. See copper hydroxide as well and is pale blue though this forms from high pH independent of the TA level. It's copper oxide that is darker.
Re: Low TA and ALK adjusted to normal levels lead to blue po
In the future, I would recommend that you avoid using sodium carbonate and only use sodium bicarbonate to recover from a zero TA situation, especially when copper is suspected to be in the water.
Also, do you know why the CYA is only 50 ppm if they have been using primarily tabs for at least a full season?
In the future, I would recommend that you avoid using sodium carbonate and only use sodium bicarbonate to recover from a zero TA situation, especially when copper is suspected to be in the water.
Also, do you know why the CYA is only 50 ppm if they have been using primarily tabs for at least a full season?
y_not
0
Re: Low TA and ALK adjusted to normal levels lead to blue po
Why would you use baking soda to correct a low TA & PH problem? True it raises both pH and TA, but the latter to a much lesser extent. So since he was starting with zero for TA, to get up to the minimum of 90, he would have to horribly overshoot pH to get there. Then it would have to be followed up with MA and quite likely aeration to bring pH back up. That is depending on how far you'd have to overshoot the TA to compensate for the whole mess.
Sounds like an absolute nightmarish endeavour that I would not wish to undertake.
I would have done exactly what he did with adjusting things with both chems.
Chemically I just can't fathom a reason as to why using bicarbonate solely, would prevent the precipitation of the copper. Also, it turned blue because it oxidized in the presence of CL, which I would think bringing the TA and pH inline allowed the CL to oxidize the copper once it came out of solution.
But I'm no Chem Geek.
JamesW said:
Why would you use baking soda to correct a low TA & PH problem? True it raises both pH and TA, but the latter to a much lesser extent. So since he was starting with zero for TA, to get up to the minimum of 90, he would have to horribly overshoot pH to get there. Then it would have to be followed up with MA and quite likely aeration to bring pH back up. That is depending on how far you'd have to overshoot the TA to compensate for the whole mess.
Sounds like an absolute nightmarish endeavour that I would not wish to undertake.
I would have done exactly what he did with adjusting things with both chems.
Chemically I just can't fathom a reason as to why using bicarbonate solely, would prevent the precipitation of the copper. Also, it turned blue because it oxidized in the presence of CL, which I would think bringing the TA and pH inline allowed the CL to oxidize the copper once it came out of solution.
But I'm no Chem Geek.
Re: Low TA and ALK adjusted to normal levels lead to blue po
The issue with using pH Up is that it can overshoot the TA if you use it for adjusting pH. Whether this happens or not depends on how much carbon dioxide outgassing has occurred. However, using baking soda to adjust the TA then has the pH be too low even though it does raise the pH some. Usually what is required, if only using these two chemicals, is to use pH Up to adjust for the pH and TA together but stopping when it hits the TA which it should do first, and then aerating the water to get the pH up the rest of the way. Instead of aerating, one could use a pure base at this point where 20 Mule Team Borax is reasonably close (lye would be more pure), but if one goes this route then one should stop before the TA target because adding a base will raise both pH and TA (though raises TA half as much as pH Up).
Another approach would be to use a pure base (lye) to raise the pH and TA until one gets close to the pH target and then use sodium bicarbonate (baking soda) to raise mostly the TA the rest of the way. This is the technically cleanest way to do this, but it would require a pure base which we don't normally use in pools (i.e. lye).
As for metals in the water, it's more important to just raise the pH and TA slowly. Then again, one might consider precipitating in the water as a good thing since this can get filtered out and is a way of removing the copper. The problem is if this precipitation results in staining of pool surfaces.
The issue with using pH Up is that it can overshoot the TA if you use it for adjusting pH. Whether this happens or not depends on how much carbon dioxide outgassing has occurred. However, using baking soda to adjust the TA then has the pH be too low even though it does raise the pH some. Usually what is required, if only using these two chemicals, is to use pH Up to adjust for the pH and TA together but stopping when it hits the TA which it should do first, and then aerating the water to get the pH up the rest of the way. Instead of aerating, one could use a pure base at this point where 20 Mule Team Borax is reasonably close (lye would be more pure), but if one goes this route then one should stop before the TA target because adding a base will raise both pH and TA (though raises TA half as much as pH Up).
Another approach would be to use a pure base (lye) to raise the pH and TA until one gets close to the pH target and then use sodium bicarbonate (baking soda) to raise mostly the TA the rest of the way. This is the technically cleanest way to do this, but it would require a pure base which we don't normally use in pools (i.e. lye).
As for metals in the water, it's more important to just raise the pH and TA slowly. Then again, one might consider precipitating in the water as a good thing since this can get filtered out and is a way of removing the copper. The problem is if this precipitation results in staining of pool surfaces.
Re: Low TA and ALK adjusted to normal levels lead to blue po
So the copper level in the pool was 1.7 after I put a sequestering agent in. Now I am going to do a partial drain and refill.
So the copper level in the pool was 1.7 after I put a sequestering agent in. Now I am going to do a partial drain and refill.
- Jun 20, 2012
- 439
Re: Low TA and ALK adjusted to normal levels lead to blue po
That's an insanely high level of copper. I think you should consider draining the whole pool and putting in all new water and starting over. You should also carefully inspect your customer's heater, as it has certainly been severely damaged.
PJ said:
That's an insanely high level of copper. I think you should consider draining the whole pool and putting in all new water and starting over. You should also carefully inspect your customer's heater, as it has certainly been severely damaged.
Re: Low TA and ALK adjusted to normal levels lead to blue po
Well
the customer just wants me to close as is.
Well
the customer just wants me to close as is.Re: Low TA and ALK adjusted to normal levels lead to blue po
I have had to deal with many zero, and very negative, TA pools. I only use sodium bicarbonate, and it always works.
The pH recovers just fine. How much bicarb moves the pH depends on where the pH starts. The lower it is, the more the pH rises. As the pH approaches 8.3, the pH rise drops off exponentially. This prevents overshooting the pH, especially locally. In fact, if the pH started at over 8.3, adding bicarb would actually lower the pH.
The problem with using sodium carbonate is that carbonate is much more likely to cause a precipitation reaction, especially if it is added too fast and there is locally high pH.
Bicarb combines with the excess hydrogen ions to form carbon dioxide and water. The carbon dioxide off gasses and the net effect is the same as adding a base like sodium hydroxide. There is no excess buildup of carbonate alkalinity.
HCO3- + H+ <> CO2 +H2O
More than half of the bicarbonate added becomes CO2 until the pH reaches about 6.35 and then the percentage decreases steadily from there.
In most cases, the pH will be at least 7.2 by the next day after adding the correct amount of bicarbonate.
When you use sodium carbonate, the more than half of the carbonate picks up two hydrogens to form carbon dioxide and water until the pH reaches about 6.35.
CO32- + 2H+ <> CO2 +H2O
Therefore, until a pH of 6.35, you're getting the same thing, only with more risk of an adverse reaction.
As the pH passes 6.35, less than half of the carbonate ions pick up two hydrogens to form carbon dioxide and more than half of the carbonate ions pick up one hydrogen ion to form bicarbonate.
In any case, I have successfully used bicarb only to recover from zero, and well below zero, TA pools.
I have had to deal with many zero, and very negative, TA pools. I only use sodium bicarbonate, and it always works.
The pH recovers just fine. How much bicarb moves the pH depends on where the pH starts. The lower it is, the more the pH rises. As the pH approaches 8.3, the pH rise drops off exponentially. This prevents overshooting the pH, especially locally. In fact, if the pH started at over 8.3, adding bicarb would actually lower the pH.
The problem with using sodium carbonate is that carbonate is much more likely to cause a precipitation reaction, especially if it is added too fast and there is locally high pH.
Bicarb combines with the excess hydrogen ions to form carbon dioxide and water. The carbon dioxide off gasses and the net effect is the same as adding a base like sodium hydroxide. There is no excess buildup of carbonate alkalinity.
HCO3- + H+ <> CO2 +H2O
More than half of the bicarbonate added becomes CO2 until the pH reaches about 6.35 and then the percentage decreases steadily from there.
In most cases, the pH will be at least 7.2 by the next day after adding the correct amount of bicarbonate.
When you use sodium carbonate, the more than half of the carbonate picks up two hydrogens to form carbon dioxide and water until the pH reaches about 6.35.
CO32- + 2H+ <> CO2 +H2O
Therefore, until a pH of 6.35, you're getting the same thing, only with more risk of an adverse reaction.
As the pH passes 6.35, less than half of the carbonate ions pick up two hydrogens to form carbon dioxide and more than half of the carbonate ions pick up one hydrogen ion to form bicarbonate.
In any case, I have successfully used bicarb only to recover from zero, and well below zero, TA pools.
- Jun 14, 2012
- 2,668
- Pool Size
- 13500
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool Edge-40
Re: Low TA and ALK adjusted to normal levels lead to blue po
Below zero TA - we are not in Kansas anymore...
-sent with Tapatalk 2
Below zero TA - we are not in Kansas anymore...
-sent with Tapatalk 2
y_not
0
Re: Low TA and ALK adjusted to normal levels lead to blue po
JamesW, thank you for that helpful info. I'll make a note of that information. I appreciate it.
I do have a question or 2 about it though. But I don't have the time ATM so I'll ask you later.
Thx.
UWV, You dork!
LOL
JamesW, thank you for that helpful info. I'll make a note of that information. I appreciate it.
I do have a question or 2 about it though. But I don't have the time ATM so I'll ask you later.
Thx.
UWV, You dork!
LOL