Our backyard "Lake Louise"

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tcfarley

tcfarley

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LifeTime Supporter
Jul 16, 2011
10
San Jose, CA
This is my first post after four years on the sidelines benefitting from the wonderful advice and camaraderie of the TFP community. So here's a long overdue thanks for all of that!

Here's what prompted me to post today:
Our backyard swimming pool is looking like a crystal clear version of Lake Louise -- our formerly white plaster has become turquoise blue, creating an overall look that my wife rather likes, but I'm concerned about who or what may be being harmed by whatever chemistry is at work here.

Problem description:
Turquoise blue staining of the plaster surface, the skimmer basket, the DE grids... anything that's white and is submerged in our pool water for a sustained period (weeks) eventually turns blue. The plaster appears to be stained -- the blue doesn't come off with nylon brushing or even wire brushing. I occasionally find small turquoise rocks (<2mm in diameter) in the bottom of my filter.

Pool condition:
Water is clear
FC: 3.0ppm
TC: 3.5ppm
pH: 7.5
T/A: 95
CYA: 70ppm
CH: 550+
Salt: 3350
Copper: >3.0ppm

Our pool chemistry has remained pretty stable at these levels since well before this condition set in.

Diagnosis:
Reading posts here on TFP led me to suspect copper in the water, and my local pool shop took a measurement today that confirmed its presence -- the guy seemed to be alarmed that it measured so high (3+ ppm).

Questions:
1. Should I care? I'm told that it isn't really harmful to the equipment or the swimmers -- that this is basically just a cosmetic thing. Is that true? If so, and given that the aesthetics are (arguably) somewhat pleasing (Lake Louise effect), then is there any need to do anything?

2. If we do need to correct the situation, then what should we do? We live in drought-ridden California, so drain/refill is not a good option -- could make me public enemy #1 around here. And besides that, I'm reluctant to do anything until I know where the copper is coming from in the first place.

Root cause analysis:
Copper piping? I don't actually know if there's copper plumbing in our 60-year old pool system. The only plumbing I can see is either PVC or galvanized, but there is copper elsewhere in our home. However, nothing in the plumbing has changed in the timeframe that this problem has developed.

Acid interaction with SWG? My automated pH system feeds the muriatic acid directly upstream of the SWG. The guy at the pool shop theorized that there might be copper in the SWG (IC-40) and that it might be better to feed the acid downstream of the SWG. My understanding was that by placing the acid feed upstream of the SWG it would help reduce the calcium buildup on the SWG plates.

Other?

Thanks in advance for any insights y'all may have.
Todd

P.S. Happy Mother's Day to all the moms out there. :)
 
Welcome to the forum. :wave: Glad you made the switch from Lurker.

Yes, the copper is alarmingly high.

This stain must be pretty doggone even throught the pool, right? Got a pic?

What does it look like at the water line? Does it transition to white rather sharply?

Do you have a pool heater?

how old is the heater?
 
Thanks, gang, for picking up the thread so quickly. I have an update!

Funny how, after pondering this situation for weeks, the culprit occurred to me while I was driving in the car not 20 mins after posting here. :p

About 10 months ago, I *ingeniusly* repurposed the old port where I used to hook up our pressure-side pool sweep, mounted an automatic fill valve (EZAutofill) there, and then tapped into the existing PVC line that fed it with a hose to a brass hose bib. Last time I checked, brass was a copper alloy, right? Doh!

Rookie mistake! That's gotta be the source of my copper, right? Every drop of water going into our pool for the past 10 months has gone through that brass bib. And that coincides pretty well with the beginning of our staining problem. (To answer your question, duraleigh, we don't have a heater. And Divin Dave, we haven't used any algeacides in recent years.)

So, if that's the source, the remaining question is what, if anything, to do about it...

Obviously, step one will be to replace the copper hose bib with a valve that isn't brass/copper. That will stop the flow of copper in, but it won't get the copper (or the stains) out.

So I think I have the same questions as before: Should I bother trying to get the copper out? (i.e., is it harmful?) I read the TFP article on ascorbic acid treatment; should that be my next step?

Thanks all,
Todd

PS Thanks for the tip about my FC/CYA, Divin Dave. When I first put in the IntelliChem, I was keeping the CYA low in order to not produce too much signal noise to the ORP sensor. (As Jason Lion said all along, ORP systems aren't a great fit with a SWG.) However, my practice now is to not use the ORP control system, so I guess there really isn't a reason for me to be skimping on my CYA level any more. Thanks!
 
I am not sure the source of your stain but the hose bib is NOT it. We'll have to keep thinking on it.

Ascorbic acid may be helpful but I would identify what the stain is and what's causing it first.
 
duraleigh said:
I am not sure the source of your stain but the hose bib is NOT it. We'll have to keep thinking on it.
Click to expand...

Really? Darn. I thought we had it.

The only products I've knowingly put in the pool have been muriatic acid, salt, baking soda, CYA, and liquid chlorine.

How much copper exposure would it take to produce a 3+ ppm concentration in 22K gal of water? If (hypothetically) I were to drop an old penny (back when they were mostly copper) in the deep end of an otherwise copper-free pool for a minute, would this be the result? A roll of old pennies for a month?

Sorry, just trying to understand if a one-time event could have caused this, as opposed to a prolonged exposure.
 
Minor update: I measured the copper in our municipal fill water... just 0.1 ppm.

Recap:
- Current copper level in the pool is over 3 ppm. White plaster now a turquoise color throughout the pool. Pool light bezel has turned bronze.
- No heater. No algeacides used in past 24 months. 0.1ppm copper in fill water.
- It's a 60-yr old pool, so the underground plumbing could be copper, but I don't know why that would start showing up in the water only now, all of a sudden.

Any thoughts/theories appreciated as to what might be going on here.

Cheers,
Todd
 

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If the acid flow or any water that has higher acid levels in it, comes in contact with any cooper anywhere, that would explain how you could end up with that much copper that fast. I would be looking hard at the acid system and all water down stream from there back to the pool.

For example, If your underground pipes are cooper, they may have had scale in them. Once the flow of water with acid injected removed that scale, it would expose the copper to the low pH water. Instant cooper source .

In answer to your question a roll of pennies would do it..if you drop them in your acid tank
 
Thank you, chiefwej. That sounds plausible to me.

The acid is injected into the system just before the SWG and only 8 ft before the PVC ends and the original plumbing begins. I need to confirm that it's copper and not galvanized.

If copper, then I guess I'll look at alternate paths to the pool. I do have the old 1" PVC that used to feed the pool sweep. Or before resorting to that, maybe just reducing the dosage from the MA feed -- can't recall what it's set at now. Will check that next.

Thanks much,
Todd
 
@chiefwej -- Thanks again for your insight. Looks like you nailed it. I do, indeed, have copper underground. I called Pentair to ask what recommendations they have for owners of their MA-feeding systems with copper plumbing. They said, "Um, we don't recommend these systems if there's copper plumbing."

Ouch.

Wish I'd been bright enough to figure that out before I bought. Live and learn!

I still plan to investigate feeding the acid through my (currently unused) 1" PVC line to the in-wall port for our died-and-gone pool sweep. I'll post any positive results here, on the off chance anyone else makes as dumb a mistake as I did!

Meantime, I guess I'll be investing in some Jack's Magic purple, based on the advice I found here on TFP.

Sincere thanks to all who pitched in on this thread. Much appreciated!
Todd
 
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