Hopefully this belongs in this thread.
I transferred a tank and put new water, same old sand and was told by an aquarium joint that I could put the dead rock that came with the deal back into the system no problem. Seems I may have been told some bad advice because the nitrate level was around 160ppm and after doing a 60% water change, adding a cleaning crew and some nitrate eating plant (I think cabomb) they're down to 60ppm. Will the dead rock and old sand continue to play havok with my nitrate levels?? Should I scrap the rock and buy live rock? I used some instant nitrifying bacteria to help put back some of the good bacteria. I don't want to end up spending loads of cash on new water to save funky rock.
The rock isn't the issue at hand. What you are dealing with is the wonders of transferring a tank. For as long as the tank was set up, food and poop end up filling the sandbed...and moving it released all of it! That is why your nitrates are through the roof.
If you bacteria in a bottle wasn't expired, it might help out some...but until things are settled with the sandbed you'll have to keep up with the water changes to get the nitrates down. This is why we usually recommend you ditch any used sand in transfer tanks.
Would it be best to replace the sand or add more "live" rock?
Water changes are helping, the nitrates are "down" from 80-160 to between 40 and 60ppm. I just read some where that the rocks can continue "leaching" nitrates into the water and I wanted to make sure I didn't continue to waste money on water changes if I could just change the rocks and get it over with.
Water changes are the most effective and cost efficient way to manage parameter issues.
In this case, it is the sandbed causing everything going on. If you want to replace the sandbed, go for it. It will be a long process doing so and you'll want to make sure you don't knock the rocks over and break the glass...that would be a disaster.