Copper Carbonate Problem

[Kelvin32]

A week or so ago our 10 year old heater gave out -- it started leaking a noticeable amount of water, and a technician opened it up, showed me part of the disintegrating core, and said it was not worth repairing and should be replaced, so we did.

Previous to this I had noticed the ph was very low, perhaps close to 6.0, and subsequently it of course remained so. After the new heater was installed, over the course of a few days I dumped 4-5 lbs of sodium carbonate based "ph+" into the pool, which is ~15,000 gallons. The ph was still low, ~6.5, when my sister and her kids came over for the afternoon. There were a bunch of us in the water for over an hour, and some of us came out with blue staining on skin, hair, and swimwear. Most of this proved easy to wash out. The water also had a very hard taste, and the "hardness" square on a test strip is very very high. After searching around a bit I realized this of course was probably high copper content, presumably from bits of broken off and dissolved heater core, so I got some "Stain Prevent" liquid intended to "make pool minerals and metal inactive" and "Pool Water Clarifier", a powder which is added through the skimmer to form a "jelly mat" in the sand filter to help strain out fine particles.

The latter recommended the ph and alkalinity, which was also very low (~30-40 ppm), be brought into balance. I added about 10 lbs. of presumably bicarbonate based alkalinity booster and another 2-3 lbs of ph+.

This raised the alkalinity and ph somewhat but they are still too low, I think about 6.8 and 50-60 ppm based on test strips; I went ahead with the Stain Prevent and Clarifier anyway since there was enough for several doses.

The next day I found large areas of what I now believe is some kind of presumably very diffused but crystalline copper carbonate sediment.



Vacuuming this up works somewhat in that part of it does get trapped in the sand filter and can be backwashed out, but much of it very visibly just comes back out the jets, so the only thing I've been able to do is dump it straight out via waste. Unfortunately, it is very fine and easily disturbed, so after one 15 minute session (which lowered the water level by 1-2") I still only removed perhaps 10-20%; I'll be able to guesstimate better once it settles again. A very tedious cycle.

Does anyone have any suggestions about this? Am I wrong about it being copper carbonate? That is a bit worrying since wikipedia notes it is an effective algaecide (in fact, I think used in pools as such), but also potentially "toxic to humans".

 

[JoyfulNoise]

It doesn't really matter what the copper is as your water is laden with copper from the previous heater rotting out. More of problem is your water's pH is WAAAAAY TOO LOW. It also sounds like your pH and TA recently crashed (probably because the pool is using acidic trichlor pucks) which is now rotting out your new heater.

You need to keep adding soda ash (sodium carbonate or pH-Up) or Borax (20-mule team borax) until your pH gets back into the mid-7 range and your TA goes back up.

Also, you need to click on Pool School above and review the ABC's of Pool Water chemistry. Your pool water, from what you describe, is totally out of chemical balance. You will need to be exceedingly careful here because if your water is larded up with copper form the previous heater, any chlorine you add at pH above 7.5 will cause serious copper staining.

We can help you, but you need to give us more information about your pool (please fill out your signature line), your location (where is Keswick?) and you need a good test kit (either a Taylor K-2006 or a TF-100 from TFTestkits.net). We absolutely can not and will not give advice off of pool store testing as it is highly likely that the pool store advice is what has gotten your pool water to this state of unbalance.

 

[Kelvin32]

Thanks for the help, I've added my exact location and some details about the pool in my sig including a revised estimate of the volume (it is probably not more than 10,000 gallons). And I will read the ABC thread.

It doesn't really matter what the copper is as your water is laden with copper from the previous heater rotting out. More of problem is your water's pH is WAAAAAY TOO LOW. It also sounds like your pH and TA recently crashed (probably because the pool is using acidic trichlor pucks)

Yes, I believe the pucks are such. I take it I should stop using them until I get this sorted?

Although it's a bit tangential, as background about how things ended up this way: It's my mom's house, she's 76, I'm 43, and I end up doing most of the work but she can be a difficult blend of (bluntly) stubborn and technically inept and has her own sometimes quite wacky conceptions about the physical world ("Why I've been doing this like this for years and it is fine"). Alkalinity and ph are not issues she has ever expressed concern about, just making sure there's enough chlorine to kill bugs, and it is only because of itchy skin and eyes that I've managed to get her taking it seriously. Hopefully the wrecked heater and current state of affairs help in driving some points home.

which is now rotting out your new heater.

Really? So fresh copper could be coming from the fresh heater because of the acidity?

You need to keep adding soda ash (sodium carbonate or pH-Up) or Borax (20-mule team borax) until your pH gets back into the mid-7 range and your TA goes back up.

Will do. It's my understanding that getting the ph up may be more difficult if the TA is too low, but sodium carbonate (as opposed to bicarbonate) is intended to raise the ph without affecting the alkalinity, which is why I switched to using the alkaline booster instead.

You need a good test kit (either a Taylor K-2006 or a TF-100 from TFTestkits.net). We absolutely can not and will not give advice off of pool store testing as it is highly likely that the pool store advice is what has gotten your pool water to this state of unbalance.

I'll try and find one; the current pair o' droppers test kit is actually just ph and chlorine, which is why I got the strips from a local hardware store. Unfortunately the pool place closed up earlier this year and now the nearest one is a bit of a drive.

 

[JoyfulNoise]

Yes, I believe the pucks are such. I take it I should stop using them until I get this sorted?

Yes, remove any pucks immediately and switch to chlorinating liquid (aka, bleach) only until this gets sorted out.

Really? So fresh copper could be coming from the fresh heater because of the acidity?

Yes, if your pH is below 7.0 then the pool water is continuing to etch the heater surface adding fresh copper to your pool water.

Will do. It's my understanding that getting the ph up may be more difficult if the TA is too low, but sodium carbonate (as opposed to bicarbonate) is intended to raise the ph without affecting the alkalinity, which is why I switched to using the alkaline booster instead.

NO! Sodium carbonate (soda ash or washing soda) raises BOTH pH and TA. Alkalinity booster is sodium bicarbonate (baking soda) which raises TA but only slowly affect pH. Borax raises pH without raising TA much. If your TA is still low then use soda ash.

I'll try and find one; the current pair o' droppers test kit is actually just ph and chlorine, which is why I got the strips from a local hardware store. Unfortunately the pool place closed up earlier this year and now the nearest one is a bit of a drive.

You won't find a Taylor K-2006 or a TF-100 in any local pool store. They can only really be purchased online. I see your in Canada, that is unfortunately going to make it harder to get one of the test kits we recommend because Lowry & Associates has a complete monopoly on the sale of Taylor Testkits in Canada and TFTestKits.net is a US-based company and cannot ship into Canada. If you knew someone in the US you could have them order it and then go get it from them, but it's still a hassle. Lowry will sell you a test kit like the K-2006 but they will charge almost 3X the price of what they retail for here in the US.