Sequa-Sol was a blend of citric acid and sodium hexametaphosphate, and possibly other stuff that they didn't have to list in the MSDS. I don't know if that's STILL what it is; manufacturers are not bound to keep a formula the same, and often reformulate without notice.

I don't understand why the pool would cloud after adding sequa-sol, unless your calcium was high. I don't understand why citric acid + SHMP would remove -- as opposed to sequestering temporarily -- copper. But, if it worked, it worked!

One possibility is that the cloud was calcium phosphate, which is very hard to filter UNLESS you have a DE filter. And, I'm pretty sure that copper will aggressively stain calcium phosphate surfaces. So, if you coat your filter with calcium phosphate, and the collect the copper on the calcium phosphate, and *then* clean your filter, voila', down the drain goes the copper.

But, that's a lot of guessing. Again, I don't really know what was happening.

Lemme go in a different direction for a moment. You don't quite say so, but you imply that the copper came from your heater. I *have* seen mega-copper levels where people with pool heaters let their pH get really low OR where they feed trichlor upstream of the heater. Copper only comes from heaters if something is badly wrong with the water chemistry inside the pool heater. THAT is something you need to fix.