My 75 gallon tank has been cycling for a little while now without any fish in it. I added a food pellet to introduce some ammonia into the tank and after a day or so it hasn't dissolved properly, there also seems to be some weird white sludge on top of it. I poked it with a prod and it came apart. Now the white sludge is sort of floating in the tank. There isn't much of it but I just wanted to know if its anything to be concerned about?