well water into pond

Question
We have a large pond/lake behind our house and I want to know if we pump well water with high mineral counts into the pond, to replenish the water, if it will affect the ecosystem of the pond.

Answer
Get your well water tested.  In some localities, it's a free service provided by local government.  It could be bad if, say, there's a concentrated amount of lead.  Most likely, it wouldn't contain anything bad.  Keep in mind that algae feeds off of some nutrients so you may encounter some elevated algae levels.  Consider yourself lucky that you don't need to dechlorinate 20,000+ gallons of water.