That's a relief. I have encountered some pretty horrible recommendations over the years by 'chemists' who were not water treatment specialists, so you really scared me. For what it's worth, mercury contamination would not necessarily have been irritating.

On the other hand, copper stains pools. If that's a concern (it doesn't bother everyone), you'll need to be cautious as you add chlorine.

Regarding your original comments:

+ CYA is one of the most critical measurements on an outdoor pool. It's very difficult to manage an outdoor pool correctly without knowing this. Most algae problems come because people do not understand that chlorine levels have to be determined based on your CYA level. Of course, some people get lucky, and do the right thing by accident. If you are naturally lucky, that's always an option.

+ Low hardness does not cause 'floaters'.

+ Dichlor and trichlor are 2 different chemicals. Both are forms of stabilized chlorine, but have somewhat different properties. The percentages you list don't correspond to undiluted products, so I'm guessing you are buying one of the diluted forms of those products. Dilutants can include borax (harmless or even helpful), magnesium sulfate (harmful to your pool), aluminum sulfate (mostly useless, but potentially harmful to concrete pools), copper sulfate (effective algaecide; effective staining agent) and so forth. You can check the "available chlorine %" to be sure. Trichlor should be 89% or higher available chlorine; dichlor should be either 56% or 61%.

+ Regarding the patches themselves, I have no idea. I can't recall ever seeing anything that would fit that description, but it doesn't sound like you could get a photograph of them. So I can't help with that.


Good luck!