White Substance growing in tank.

Question
I have a cottony/fuzzy substance growing all over my tank.  It seems to be coming up out of the gravel, and it is forming around the submersible heater, plastic plants and filter tube.  Can you possibly tell me what it is, and how to get rid of it?  It doesn't seem to be bothering the fish, but it looks nasty.

Answer
Sounds like a fungus growing from most likely old food decaying under the gravel. You will want to clean out the fungus and vaccuum the gravel to remove the decaying food. Watch the fish for any signs that they pick up the fungus, typically they will not in your situation but it is possible.
When feeding take into consideration that the size of their eye is the size of their stomach, they should consume all the food you place in which means you may have to feed a smaller amount to figure out what amount is adequate for your fish. Best of luck and happy fish keeping.