Help With Water Quality

[1309mw]

For around 4 years i had a Midas in a 55 gallon tank and she was perfect. 3 years ago i moved out to the country and changed to well water. Slowly as time went on she got harder and harder to keep healthy until 3 months ago when she was put out of her misery. After a few days without a water change she would turn dark orange and lay on the bottom of the tank but as soon as i changed the water (even as low as a 10% change) and she would be up and back to her original colors within 2 hours.
I now have a few other fish (yes, even knowing what happened last time, my fish addiction would not allow me to have an empty tank) including a pair of breeding jewels, a peacock and a large gourami that have all seemed to do very good (including breeding by the jewels) as well as a 30 gallon (only some mollies and neon's for the kid) and a 10 gallon that have all been running since i moved in and never had a problems with the 30 or 10.
I ran what seems like hundreds of the standard tests on the water while the midas was sick and never had anything that would alarm me.
Could this have been the well water that made her so sick?
Could it have been her aging?
Is there any tests that should be run on well water that tests for different things then the standard tests?
Any advice or comments are appreciated.
Thanks

 

[1309mw]

I do have an air pump pushing thru a stone and have a 50 and 20 gallon filter on different ends of the tank.

 

[Hawkfish3.0]

What tests do you consider "standard"? Also, has the well ever been tested (by a professional well water tester)? Do you live in an area that is heavily farmed with use of pesticides and other chemicals?

 

[1309mw]

i do sit on 40 acres of land but the field is only used for hay. So there i would think that arent very many chemicals used. The standard tests refer to the simple test that you get at lfs that test for nitro, ammonia, etc. I am only renting so "no" i havent hired anyone to test the water.

 

[Hawkfish3.0]

i do sit on 40 acres of land but the field is only used for hay. So there i would think that arent very many chemicals used. The standard tests refer to the simple test that you get at lfs that test for nitro, ammonia, etc. I am only renting so "no" i havent hired anyone to test the water.

Having the well water tested may be in your best interests anyway. I'm not sure how your relationship with your landlord is, but you may ask him/her if it's been done recently, and if they might think about doing so. If it's killing your fish (IF), you would certainly think twice about consuming it.