Just checked my 60g dt ammonia with hanna is 0.05. So its not the checker. I will check the prepared water tomorrow. I agree I know I need to do a water change just keep hoping it will trend down and it doesnt.It never hurts to check your instrument/kit against another system, especially if that system has tests results from a different instrument. It may not tell you which one is correct if they are different. If they are close it can give you some peace of mind.
Even bottled bac is going to take a day or three to do its thing, depending on how out of balance the system is and how much bacteria is in the bottle compared to the load it has to multiply and process.
When you scoop and move sand, the shear and crushing forces will kill a tremendous amount of the macro fauna living in it. If there were nems, crabs, isopods, mini stars, etc. mixed in, then they were likely damaged and/or ground into the sand as it was removed and replaced.
I would be considering a water change even if what is left is looking a bit better.