Staining In A Copper Ionized Pool

[poolchick]

This may have been discussed before but I am new today and I really havent looked through everything.

First of all I am in Ontario Canada , not sure why that would be important but I thought I would share

Ok heres the scoop. I have a customer that is running the ecosmart system, which is technically not legal here but that is neither here nor there, anywho we were closing her pool today and the boys noticed that when the water level was lowered that there is a lime green tinge to the liner that wasnt there before. I am aware that copper will turn green when ionized on say a roof or something but havent seen this in a pool before. Any suggestions on what to use to clean it?

Her pH, alkalinity and copper levels have been in range all summer long. I am at a loss as to what to recommend.

Thanks

[Pool Clown]

It sounds like copper sulfate. Its when the Ph drops to a point where it begins to erode the copper parts more readily. Copper, like in the heater. If the Ph is ok, then there is one other way you could get this. When Certain algecides are not diluted properly before they were introduced to the pool. If you had plaster, you could've acid washed. I don't know how aggressinve you can get with a liner, I don't have much dealings with liners.

[chem geek]

The copper came from the EcoSmarte system since that's how that system works. The copper is intentionally added to prevent algae growth and presumably to prevent bacterial growth though copper is not very fast for that. The staining is likely to have occurred when the pH rose since with EcoSmarte you have to keep the pH relatively low close to 7.0 due to the fairly high levels of copper that are used. At higher pH, copper precipitates with both carbonate and hydroxide to form green copper carbonate (see here), green copper hydroxide (see here), and/or black copper oxide (see here).

All of these stains can often be dissolved with mild acidic conditions, but then the copper that is dissolved needs to get bound by a metal sequestrant that is added or else it will just re-precipitate again when the pH goes up. Another option is to remove the stain with a mild acid (and near 7.0 pH water in the pool) and then do a water replacement to remove the copper. HOWEVER, vinyl liners don't tolerate acid very well at all so that makes it difficult to remove the stain. You can use Jack's Magic "Copper & Scale Stuff" shown here and note that you must bypass any copper heat exchanger since this would remove copper from the heater as well. Basically, the pH is lowered into the mid-6's with low TA. They mention other alternatives that take longer, but generally speaking Jack's Magic has good products for stain prevention and removal.

Richard