Strange blue cloudy color to water

[kirbinster]

Just opened my pool, and it looked fairly good, just slightly cloudy. Put some chlorine in and turned on the pump and came out to a pool the next morning that was very cloudy the next morning and I could not see the bottom. Added more chlorine and checked and found pH down around 6.4. I had lost my heatpump at the end of last season and it had dumped all the Freon R22 and oil into the water - yuk. So besides adding more chlorine I added two boxes of Borax (20x40 IG pool). That brought the pH up to about 6.6 so I dumped the other two boxes of Borax I still had in and it is sitting at 6.9 right now. Dumped a pound of shock and two large bottles of Chlorox in - that is all I had on hand this afternoon. I am very perplexed at the blue color on the filter of my robot as I have never seen this color blue in the pool before. I had some sediment in the little jar that lets you see what is going to waste when you backwash the filter and I poured it out onto an old white table. It is very fine blue material. Any clues what this might be or how to clean it up. Pictures below:

 

[Donldson]

How long was your pump running with that low of pH? That looks a lot like copper patina, which could result from extremely low pH running through a copper heat pump. What is your current TA reading?

 

[kirbinster]

How long was your pump running with that low of pH? That looks a lot like copper patina, which could result from extremely low pH running through a copper heat pump. What is your current TA reading?

Well the old 19 year old heat pump gave up the ghost the end of last season and the pool was closed about two weeks after it died. The heat exchanger was titanium but there was copper piping that was in contact with the pool water from the freon size which got filled with pool water. I vaguely recall that the pH was a little low at the end of the season, but was still above 7. The new heat pump has not been valved in yet, and won't be until the water chemistry is correct. Total alkalinity is around 80 or so.

 

[Donldson]

Glad it isn't from your new heater. Couple more questions though:

Do you have any other copper pipes? Did you use a copper algaecide when you closed the pool? I have seen this before and am pretty sure it is copper, possibly mixing with the borates in the borax to create copper borate, just trying to narrow down where it came from.

How did you measure pH that low?

Finally, are you using anything other than liquid chlorine to chlorinate your pool? What was in the shock you used?

In this form it will filter out, as you have noticed, so just continue to run the filter and clean it out as you get your pH in line. The next issue, however, is that you obviously have copper in your water. This could cause staining problems if you raise your pH too much so try not to overshoot as you get it back in to range.

 

[JoyfulNoise]

It's definitely a copper compound, but highly unlikely it's copper-borate as there are no easily formed copper-borate salts. My guess would be that the locally high pH conditions caused by the borax caused the formation of a copper hydroxide or copper carbonate precipitate. It could be a precipitate with borate mixed in it, but copper borate as a well defined chemical species does not readily exist.

Either way, it is clear that there is a significant load of copper in the water that should be tested for. At the extremely low pH of the initial water (somewhere less than 6.5), the cupric ion is stable in solution. However, as you begin to raise the pH, copper will want to precipitate out of solution (as you've just witnessed). So, you need to determine how much copper you have in the water and you might need to do a significant water exchange to get rid of it. If you raise your pH too fast, there's no way to predict how it will scale out. Vinyl liners are usually not as susceptible to metal scaling but it's not impossible. One way would be to raise the pH very slowly and stuff a bunch of paper towels into the skimmer. If the copper precipitates as particulates suspended in the water, then the paper towels will act like filter paper and take them out. People have done this for iron-laden water when raising chlorine levels.

 

[kirbinster]

Glad it isn't from your new heater. Couple more questions though:

Do you have any other copper pipes? Did you use a copper algaecide when you closed the pool? I have seen this before and am pretty sure it is copper, possibly mixing with the borates in the borax to create copper borate, just trying to narrow down where it came from.

How did you measure pH that low?

Finally, are you using anything other than liquid chlorine to chlorinate your pool? What was in the shock you used?

In this form it will filter out, as you have noticed, so just continue to run the filter and clean it out as you get your pH in line. The next issue, however, is that you obviously have copper in your water. This could cause staining problems if you raise your pH too much so try not to overshoot as you get it back in to range.

No copper pipes in the systems at all. The only copper was from the refrigerant side of the old heat pump. When I took it out and cut it up a few weeks ago the entire compressor was filled with pool water from when it failed last year, so I imagine a lot of copper got in the pool from that before I closed it. Have never used any algaecide in the pool ever. I first saw the pH was low just using some multi test teststrips. I then got out my wet chemicals and measured it to be sure. Good Idea about not overshooting the pH, I'll leave it where it is at until I get all this garbage out through filtration.

- - - Updated - - -

It's definitely a copper compound, but highly unlikely it's copper-borate as there are no easily formed copper-borate salts. My guess would be that the locally high pH conditions caused by the borax caused the formation of a copper hydroxide or copper carbonate precipitate. It could be a precipitate with borate mixed in it, but copper borate as a well defined chemical species does not readily exist.

Either way, it is clear that there is a significant load of copper in the water that should be tested for. At the extremely low pH of the initial water (somewhere less than 6.5), the cupric ion is stable in solution. However, as you begin to raise the pH, copper will want to precipitate out of solution (as you've just witnessed). So, you need to determine how much copper you have in the water and you might need to do a significant water exchange to get rid of it. If you raise your pH too fast, there's no way to predict how it will scale out. Vinyl liners are usually not as susceptible to metal scaling but it's not impossible. One way would be to raise the pH very slowly and stuff a bunch of paper towels into the skimmer. If the copper precipitates as particulates suspended in the water, then the paper towels will act like filter paper and take them out. People have done this for iron-laden water when raising chlorine levels.

How does one test for copper? Why would I need to do a water exchange to get the copper out if it precipitates, shouldn't I be able to just filter it out? Not sure I understand why you suggest paper towel, won't it just filter out in the DE in my filter. As you can see it is filtering out on the screens from my pool robot.

 

[JoyfulNoise]

How does one test for copper? Why would I need to do a water exchange to get the copper out if it precipitates, shouldn't I be able to just filter it out? Not sure I understand why you suggest paper towel, won't it just filter out in the DE in my filter. As you can see it is filtering out on the screens from my pool robot.

The pool store can give you an idea of what the Cu level is. If it's over 0.3ppm Cu then you have too much in your water.

Some will precipitate out. Some of it can stain. Some it will remain in the water as copper ions. The only way to truly get rid of metals is to drain and add fresh water back in. If you choose to live with metals in your water then you have to be careful to manage your pH and chlorine very closely or else you risk recurring metal stains.

The paper towel trick is to help speed up removal. A DE filter can capture small precipitates but then you have to backwash it more. Better to use something easily disposable like paper towels or old dish rags then to mess up your filter. It's up to you.

 

[kirbinster]

Gotcha, thanks that makes a lot of sense about the paper towel when you put it that way.

Went out this morning and found a very light fluffy layer of greenish-blue floc on the bottom of the pool. Manually vacuumed it up the best I could but some of it just floats away as you get near it cause it is so light. I also put some paper towel in the skimmer I hooked the vac too so you can see what it looks like. Took a picture of that and what was on the stairs. Wonder how long it will take to get all of this. The pool is still around 6.7 pH but from what I am hearing you guys say I should probably keep it on the acidic side till I get this stuff all out is that correct? Thanks

 

[kirbinster]

Pool is starting to look a little better since I vacuumed all the fluffy stuff out. It is fairly clear in the shallow end as you can see below, but still cloudy in the deep end. Added a bag of baking soda to help raise the alkalinity, but have not done anything on the pH yet as I want to get all this copper out. I bought a cheap HTH Cl / pH test kit while I was at Walmart as I was thinking my chemicals may be off since they are a year old. I did a quick test and the pH looks like it is about 6.8 to 6.9 but the chlorine levels make no sense at all. Does the copper totally screw up the cheap one solution test? The test is supposed to show different levels of yellow but as you can see the results came out a deep dark orange which makes no sense at all.

 

[JoyfulNoise]

You need to run a DPD-FAS titration for chlorine, strips are worthless. The OTO test is telling you that your total chlorine is way above 10ppm. Given how much chlorine you added initially (post #1), it's not surprising.

Please post results from a K-2006 or TF-100 and we can advise. Stop dumping chemicals randomly in the water (like baking soda) as you're just making this harder on yourself.

 

[kirbinster]

You need to run a DPD-FAS titration for chlorine, strips are worthless. The OTO test is telling you that your total chlorine is way above 10ppm. Given how much chlorine you added initially (post #1), it's not surprising.

Please post results from a K-2006 or TF-100 and we can advise. Stop dumping chemicals randomly in the water (like baking soda) as you're just making this harder on yourself.

Not sure why you think the chlorine is that high, but I'll do a titration. I have only added one pound of shock and four bottles of Chlorox into a 33,000 gallon pool that showed as zero free chlorine to start with. I added the baking soda as the total Alkalinity was low at about 50.

 

[JoyfulNoise]

I trust that OTO test more than I trust test strips. And that OTO color indicates a TC > 10ppm. So unless your OTO reagent has gone bad, you have very high FC.

50ppm, in the grand scheme of things, is not that low. Plus, it's also based off of test strip data that is likely wrong given the discrepancy between the FC recorded there and the OTO data.

 

[kirbinster]

Well you were right about the Chlorine. It was over 10ppm when I checked it correctly. Guess my mistake was trusting the test strip when I first opened the pool. I think the acid level messed up the test. I went to the pool store and had them test everything today. Here is what they came up with:

FC = 11.64ppm
TC = 11.64ppm
CC = 0
pH = 7.3
Hardness 10 ppm
Alkalinity 60 ppm
Cyanuric Acid 48 ppm
Copper = 2.4 ppm
Iron 0.3 ppm

SO, even after getting so much blue copper stuff out of the pool it is still quite high. SO they sold me some magic pool store liquid that is supposed to remove the Copper. Unfortunately it does not say what is in it so I guess I will just hope it works. It is called Sparkle Conchelate, so I am assuming it binds with the copper so it will filter out. They told me I have to wait for the Chlorine to drop down to 2 ppm before I can use it.

They also told me that I want to raise the Alkalinity, which I am ok with. They insist that I also need to raise the hardness, but I am not sure I buy that. Since it is a vinyl pool why would I need to have calcium hardness as there is no plaster to leach. Am I correct?

 

[JoyfulNoise]

The "stuff" that they sold you will not help. It is mostly EDTA which is a chelation agent. However, the minute you start adding back chlorine, the chlorine will destroy the EDTA and you'll get copper staining.

At this point your pool water is completely fouled with copper metal. The easiest way to deal with this is to partially drain your pool and remove as much of the copper as possible to get below the 0.3ppm limit. At 2.4ppm, you are over 8X the level at which copper will scale out of solution. That is why you have blue crystals everywhere, your water has a high concentration of copper metal ions in. Trying to fight this chemically will just be an enormous waste of time and money.

How much water can you reasonably drain from your pool without your liner or pool walls being compromised?

 

[Charlie_R]

Since you posted pool store results, can we assume that you don't own either a TF-100 or K-2006 test kit? Very strong suggestion: If you don't have one, get one. Like everyone else here that bit the bullet and bought one, you will wonder how you got along without it.

Most everyone here knows that test strips are only good for about 3 months from the date of manufacture. No telling how long they sat on the store shelf, either.

Joyful has given you the best advice for dealing with the copper issue in your pool. Please save yourself a huge amount of aggravation, and do as suggested.

 

[kirbinster]

The "stuff" that they sold you will not help. It is mostly EDTA which is a chelation agent. However, the minute you start adding back chlorine, the chlorine will destroy the EDTA and you'll get copper staining.

At this point your pool water is completely fouled with copper metal. The easiest way to deal with this is to partially drain your pool and remove as much of the copper as possible to get below the 0.3ppm limit. At 2.4ppm, you are over 8X the level at which copper will scale out of solution. That is why you have blue crystals everywhere, your water has a high concentration of copper metal ions in. Trying to fight this chemically will just be an enormous waste of time and money.

How much water can you reasonably drain from your pool without your liner or pool walls being compromised?

That is a good question as far as how much can I drain, I really don't want the liner lifting. The solution to pollution is dilution, so would I get anywhere if I drained say 3-4" a day and then added that much back and then repeating for a week or two? Is there really no way to chemically bind this stuff and filter it out? I am at the point now where I have no more blue stuff coming out of solution, so it is all dissolved now.

 

[JoyfulNoise]

That is a good question as far as how much can I drain, I really don't want the liner lifting. The solution to pollution is dilution, so would I get anywhere if I drained say 3-4" a day and then added that much back and then repeating for a week or two? Is there really no way to chemically bind this stuff and filter it out? I am at the point now where I have no more blue stuff coming out of solution, so it is all dissolved now.

Yes, it is always possible to do serial dilutions but, given the size of your pool, 3-4" at a time will waste an enormous amount of time and water. Your best bet would be to drain it as far as you can safely and then refill and test.

You can look up ProTeam's MetalMagic product line. They have a process for using high-dose sequestrants based on phosphonate chemistry to precipitate a calcium-phosphonate insoluble salt that will have metal included in it. The problem is there is no way to know how effective the treatment will be beforehand (how much metal will actually get removed). As well, the high does sequestrant that remains behind will bind the rest of the metal ions up making it difficult to measure their concentration without a very expensive metal test kit (most pool stores use a very cheap metal test). So it may work or it may not work. Or, it might appear to work at first but then, as the sequestrant breaks down, whatever metals that were held in solution will start to scale out again. So it's a big gamble.

Draining and dilution with fresh water is the only sure-fire way to know you are rid of the metals.

 

[kirbinster]

Yes, it is always possible to do serial dilutions but, given the size of your pool, 3-4" at a time will waste an enormous amount of time and water. Your best bet would be to drain it as far as you can safely and then refill and test.

You can look up ProTeam's MetalMagic product line. They have a process for using high-dose sequestrants based on phosphonate chemistry to precipitate a calcium-phosphonate insoluble salt that will have metal included in it. The problem is there is no way to know how effective the treatment will be beforehand (how much metal will actually get removed). As well, the high does sequestrant that remains behind will bind the rest of the metal ions up making it difficult to measure their concentration without a very expensive metal test kit (most pool stores use a very cheap metal test). So it may work or it may not work. Or, it might appear to work at first but then, as the sequestrant breaks down, whatever metals that were held in solution will start to scale out again. So it's a big gamble.

Draining and dilution with fresh water is the only sure-fire way to know you are rid of the metals.

OK, taking your advice. I just drained about 18" which is roughly 9,000 gallons. Did not want to get too low in the shallow end and risk floating the liner. Refilling it now. I realize 9,000 won't get rid of everything, but it seemed like a reasonable start. That represents about 30% of the total water. The pool is actually fairly clear today and there is no more blue coming out. I suspect this partial drain refill should knock the Copper from 2.4 to about 1.7 ppm. If I do the same thing again it would get it to about 1.2. The question I have is how necessary is it to do that? If I no longer have an issue with blue stuff and the water is clear what is the harm of having this amount of copper in the water?

 

[JoyfulNoise]

The issue with copper is that, at low pH (7.0 and lower), the Cu2+ ion is somewhat stable in solution. The moment you start raising the pH and adding chlorine (an oxidizer) in, the copper ion will start to scale out as a mixture of copper hydroxide and cuprous oxide (Cu2O). Over time, the cuprous oxide converts to cupric oxide (CuO). The early Cu staining on surfaces can look reddish-brown. Over time, the oxide scale converts to the blackish colored cupric oxide which is very difficult to remove using conventional metal stain removal & sequestrant chemicals. All of these reactions can be seen when the copper concentration is over 0.3ppm.

It's up to you on how you want to handle it. If you get the copper levels below 1ppm, then you can try to see if the copper stays stable (I doubt it). If not, you can use either Jacks Magic products or ProTeam Metal Magic products (both sequestrants) to hold the metal in solution better. The down side is those chemicals are an added expense and you need to keep up maintenance dosing all season long.

 

[borjis]

They insist that I also need to raise the hardness, but I am not sure I buy that. Since it is a vinyl pool why would I need to have calcium hardness as there is no plaster to leach. Am I correct?

In most cases that's right unless you have a heater of some kind. I know gas heaters typically require 225ppm of calcium to keep
the warranty valid.

Check the owners manual of your new heat pump to see what it's requirement is.