How much copper is too much copper?

[Jimmy_from_NZ]

Obviously if a pool is balanced and looked after, it's uncessary to add copper based algaecides or use Tri-Chlor tablets that include Copper Sulpahte.

However my question is, at what concentration does high copper become a problem? I've seen some figures suggesting that copper should always be kept under 0.2ppm. Is it possible to have quite high copper, say ~6-7ppm without copper staining as long as the ph/TA/Hardness is kept in balance?

The common algaecide sold around here contains 47g/L of Copper Sulphate, so if I added the suggested dose rate of 1L to a 50,000L (13,209 us Gal) pool this would increase the copper reading by 0.94ppm?

Cheers,
Jim

 

[JasonLion]

How likely copper is to cause stains varies with the pool surface. Fiberglass is the most prone to staining, plaster in the middle, and vinyl least prone to staining. With vinyl you can go to 0.3 and sometimes 0.4 without stains. Fiberglass is noticably lower.

If you are very careful with the PH you can keep even quite high copper levels from staining. But, depending on your chemistry, it may only take one day of inattention for PH to spike up and cause unsightly and expensive stains. It is difficult to get the PH to be stable at the required levels (around 7.2), PH likes to go up above that.