tap, tank, and bottle

[Toney]

my nitrates are up... they weren't this high out of the tap until recently. ..

I checked some bottled water just to see if it was the test solution.

 

[AbbeysDad]

High nitrates in source water. You could buy/haul water, get an RO system, or filter out nitrates from source water for weekly water changes.
I find that the most economical method is to filter out nitrates.