Wayyy too much copper--my fault!

[BorisMD]

Last season, my pool, an inground vinyl liner variety, was doing great. No algae, no cloudy, etc.

That is, until my heater core sprung a leak. What I realized was that I hadn't stayed on top of my pH, and I had slowly ionized my heater core into copper ions.

My pool guy came and replaced the heater core (very expensive lesson).

I did my water chemisty and lo and behold, when I shocked, my pool turned ash grey. What happened? I oxidized all the copper that was in solution and it came out on my liner.

Last fall, before close up, I added some citric acid, and partially drained and filled a few times to get the copper out. I also used a copper floculant, which produces tons of green copper oxide in the filter (cartridge), and requires frequent filter cleaning (big pain in the @$$).

My pool is due to be opened in one week. I'll pull the cover off this week. It will probably still be one big ice cube.

So, my plan for spring is to:
1. Make sure my pH is correct.
2. Check the copper level.
3. Continue to use floculant to get the copper out of solution (and out of my liner).
Any suggestions? I'm wondering if I should continue to try the partial drain and refill to continue to dilute out the copper out in addition to trying to precipitate it out.

Thanks,

Boris
Lake Elmo, MN

[duraleigh]

Hi, Boris,

In some way, that's a very easy answer.....dilution is 100% surefire.

The floc, may do well and then, when you shock, you'll precipitate some more. If you've got cheap water, I'd dilute the heck out of it and start over balancing my chemicals. That's probably a little more cumbersome but the easiest way to KNOW you've got it under control

[PoolDoc]

Last fall, before close up, I added some citric acid, and partially drained and filled a few times to get the copper out. I also used a copper floculant, which produces tons of green copper oxide in the filter (cartridge), and requires frequent filter cleaning (big pain in the @$$).

I'm curious; what product did you use?

I'm wasn't aware of a product that would reliably precipitate copper ONLY on to the filter.

Are you sure the precipitate was copper oxide? The only copper oxides I'm aware of are black (CuO) or red (Cu2O). Could it have been copper carbonate, which is green?

Ben

[BorisMD]

Ben, Ben, Ben,

Blast you and your vulcan logic. You've discovered my chemical laziness.

You are correct (big surprise), it probably is copper carbonate.

As for precipitating out, it's not in the filter, it's in the pool. Turns the whole pool milky, and clogs the filter cartridge within a day.

Mind you, I've had all winter to forget about this, so my memory is not completely clear (no pun intended). I believe all I did last fall was use some "super sequa sol" to bring the copper in to solution, and then added something to raise the pH (probably the soda ash), and shocked with bleach. This pretty much forced the copper into the carbonate state. Forgive me, but I don't know what reaction I was causing.

I've partially drained and refilled a couple of times, and I hope I've diluted it out enough.

I still have a liner with an unpleasant gray haze to it, I'm hoping to get that out this spring with some type of acid treatment. Any good ideas on where to get large amounts of ascorbic acid for a good price?

Thanks,

Boris

[PoolDoc]

NOTICE to ALL READERS:
The methods described below are potentially very dangerous, if you do not follow the instructions. If you are unwilling to follow EVERY step below, do NOT try this. If you are CONFUSED about any one of the steps below, do NOT try this. Be safe; it's better to have stains, than to get hurt!

As for precipitating out, it's not in the filter, it's in the pool. Turns the whole pool milky, and clogs the filter cartridge within a day.

Mind you, I've had all winter to forget about this, so my memory is not completely clear (no pun intended). I believe all I did last fall was use some "super sequa sol" to bring the copper in to solution, and then added something to raise the pH (probably the soda ash), and shocked with bleach. This pretty much forced the copper into the carbonate state. Forgive me, but I don't know what reaction I was causing.

. . .

I still have a liner with an unpleasant gray haze to it, I'm hoping to get that out this spring with some type of acid treatment. Any good ideas on where to get large amounts of ascorbic acid for a good price?

Very interesting.

It sounds like you did succeed in bringing most of the copper into solution, and then precipitated calcium carbonate with the high pH (that would be the "turned the pool milky" bit). The high pH calcium carbonate would have been trapped in the filter, and would have then been an 'attractive' place for the copper to precipitate out. This process is one I've been interested in for some time, but unfortunately don't have the system that would let me explore it.

The problem is the "unpleasant gray haze" bit, which is probably black copper oxide. My experience is that HEDP (in most liquid stain / scale agents) will lift that off plaster, if the stain is fresh, but not after it's been there for awhile. I don't know about liners. The problem with copper oxide stains is precisely the reason I haven't been able to 'play around ' with methods like what you (somewhat inadvertently?) followed: copper oxide stains ARE noticed, and are disliked.

I don't know a sure-fire answer for your situation. But, what I would recommend is a two state process. The first stage would is focused on trying to lift the oxide stains:

1. Run your circulation system 24/7
2. Make sure to adjust any jets, so that the water stream is not aimed directly at any pool surface.
3. Lower your pH to about 7.0, and operate there for the time being.
4. Maintain alkalinity levels in the 70 - 110 ppm range. If they are higher than that, try to use aeration to lower them.
5. Avoid feeding chlorine through the heater.
6. Add weekly small doses of HEDP (or maybe Sequa Sol -- I don't know what's in that produdt), but do NOT overdose. Follow label recommendations.
7. Maintain pool sanitation with low chlorine 0.5 - 1.5 ppm PLUS weekly doses of polyquat.
8. Brush the pool walls and floor regularly (at least 1x per week)
9. Adjust the CYA levels as needed. If you add CYA, allow it to dissove for at least a week, before changing to the process below.

After 2 - 4 weeks, you'll likely have lifted all the stain that's going to come up. You'll probably have to live with what's left. There is another process I've used, but it involves a relatively dangerous chemical, sodium hydrosulfite, that's become very hard to obtain, even for me. And, the reversion process, after using it, is quite tricky.

The next step is to get the copper out of the water, without restaining the walls. This next part is DANGEROUS, if you don't follow my instructions carefully. You are LIKELY to get HURT or to DAMAGE your system if you mess up. Don't even THINK about trying this, unless you can follow my instructions carefully and completely.

1. Continue to run the system 24/7
2. Use borax to gradually raise the pH to about 7.4 - 7.6.
3. Meanwhile, stop using HEDP.
4. Buy some calcium hypochlorite, and use it EXCLUSIVELY for chlorination. Make ABSOLUTELY sure you don't have any chlorine in any feeder ANYWHERE. (Cal hypo, prior to being fully dissolved in your pool, does NOT react well with other pool chemicals: very dangerous and nasty things can happen, if you allow it to come into contact with any other pool chemicals.)
5. Add small doses of cal hypo (no more than 1 ppm at a time!) (Cal hypo adds about 8 ppm of chlorine per pound to a 10,000 gallon pool. A cup of gal hypo is about 1/2 lb, so a cup is about 2 ppm, in a 10K gallon pool.)
6. Add the cal hypo DIRECTLY to the skimmer, but ONLY if the pump is running, and water is circulating freely through the skimmer. Absolutely DO NOT add cyanuric acid or stabilizer to the pool, while you are chlorinating this way! If you need to add stabilizer, stop using the cal hypo a day before using adding the CYA, and do not begin to use it again for a week after adding the CYA.
7. Do NOT clean your filter more than you have to -- as long as there's still adequate circulation, do NOT clean it.
   
8. Gradually, increase your chlorine levels from 0.5 - 1.5 to 5 - 10 ppm. Do this over a period of a week or more.
9. If your filter plugs, stop adding chlorine, and let levels drop back. THEN, clean the filter, and restart from the 0.5 - 1.5 level. Do not simply adjust back up to whatever level you'd reached before cleaning the filter -- restart from the lower level.
10. Once you've reached and held 5 - 10 ppm for a couple of days, use SODA ASH --- in very small repeated doses added DIRECTLY to the skimmer -- to raise the pH to around 8.0, while continuing to maintain higher chlorine. (Don't add soda ash and cal hypo at the same time, but you can safely add them a few minutes apart.)
11. Operate for a couple of days at pH 8.0 and Cl 5 - 10 ppm. At the end of this time, all copper should be completely gone from the water, and (hopefully) trapped in the calcium residue on your filter.
12. Clean your filter.
    
13. Lower your pH to normal levels, and retest alkalinity. It may be too high. If so, lower to 7.0, and use the aeration method to reduce your alkalinity. Do NOT add acid directly to the skimmer. If you are still using cal hypo, bad things WILL happen. Even if not, adding acid to the skimmer can remove copper from your filter media, and put it BACK into the pool water!
14. Once you've restored alkalinity levels, you can drop the polyquat, and treat the pool normally.

If you like, you can then give away the cal hypo, or continue to use it via the skimmer. BUT, if you do use it up,

• Be SURE to run the pump at least 1 hour after adding a dose of cal hypo.
• Also, use borax to maintain a pH of 7.6 - 7.8. (Borax shouldn't be mixed with cal hypo, but can be safely added to the skimmer with only a few minutes separation between borax doses and cal hypo doses.)

If you do use the cal hypo,

• Make SURE that you do not add ANY chemicals to the skimmer except borax or cal hypo.
• And, make SURE that you do not have ANY kind of chemical feeding going on via the skimmer, a pipeline, an SWG, an inline feeder, a venturi feed system, or anything else. ALL other chemicals must be added directly to the pool, if you are feeding cal hypo via the skimmer.

I'm sorry this is so long and complex, but it's the best I can do. It's not guaranteed to work, though. If you do try this, I'd love to hear how it goes for you.

Ben
PoolDoc

[BorisMD]

Thanks Ben.

Orders received and will be carried out.

I had my pool opened early so I would have time to do this before the swim season kicks in.

Question: Why use cal hypo instead of bleach? I've never used cal hypo up to this point, given that I had a vinyl liner.

Also, "super sequa sol" is a GLB product that is actually for prevention--sounds like some type of floculent. It's not what I used last fall. I used some time of "stain magnet" my local pool guy sold me. I think it was some type of acid.

I'll let you know how it comes out.

Regards,

Boris