Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
MAYBE fish load is so small that your slow growing plants are enough to handle the waste?
Nitrifying bacteria could have come in on the leaves, and that might have been just enough.
WCM are cool water fish. Allow the temperature to drop to the low 70s for them.
Alternate idea: Someone left the cap off the test (at the store) and it is not longer accurate.