Hey guys In my new setup Ive got a rena excel 300 watt heater. The heater is fully submerged so there is some of the cord in the water. What im starting to notice is that a white film from the cord is starting to peel off into the tank(almost like paper)I dont have fish in there because Im doing a fishless cycle but I was curious to know if this is normal and is it a good idea to have that stuff sitting on the bottom of the tank?When I try to remove it it just crumbles.