High ammonia level

[Sladams]

Yes, it's possible. There was another member who had a chemical problem and we determined via experiment that the gravel was the problem. Since you didn't have ammonia when you reset up the tank, I'd suggest the following:
Take a clean container and place your plastic plants in it and fill it with new water that has no ammonia. Take another clean container, place some of the gravel in it and fill with new water that has no ammonia in it. Test both containers in 24-48 hours to see if either of these are the culprit and report back.

That was me! I had to empty everything out and clean it because it was my gravel.

 

[Andy Sager]

That was me! I had to empty everything out and clean it because it was my gravel.

OOPS!!! I help so many I don't really look at the names anymore, I just answer the questions. ( At least I remembered the situation. Do I get points for that? ) I would still check them both again just to make sure. Some plastic does have the ability to absorb things so it might be them.