Flower pots have a very very poor survival rate in the home aquarium, but there are a few "pro's" here who have seem to be keepkin them alive for a longer amount of time. I dont know if you use synthetic salt of not, but it seems to be pointing to fact that the sythetic salts are missing something that cannot be replicated. that worm you have there is completely harmless, I think its a spaghetti worm! or I forget the name but harmless.