So I did a water change of 20 gallons and retested the parameters the following morning.

GH - 60
KH - 80
Ph - 7
Nitrites - 0
Nitrates - 10

I always use the same water source for my water changes. I vacuumed the entire gravel bed, leaving the filter media alone. I'm going to do another water change and test the parameters before I decide to tear this tank down.