So it's been 2 weeks since we revamped the tank.
Here's what we did:
-Removed all livestock
-Scrubbed all rock and tank free of algae
-Removed 1/2 of the sand
-100% water change
-Changed filters in RO/DI unit
Today, the nitrates are still off the charts. We're doing a 20% water change, but we're not too confident that's going to put a dent in the nitrates. With no livestock and clean water being used to top off - what could be causing the nitrates to stay so high? We checked for ammonia and nitrites a week after the revamp and neither was present, so if it did go through the 1st 2 stages of a cycle after the 100% water change, it happened very quickly.
Could the nitrates possibly be leaching out of the rock? If that's the case, I wonder how long it will take for things to go back to normal...