hey guys im just mentioning the importance of heater covers.
i had to have a heater cover when i got my
Oscar (for obvious reasons), but when my catfish killed my
Oscar 
i changed tank around, cleaned it and took off the cover?
i then went on holiday for 2 weeks, when i came back my clarias cat was
really badly burned in several places, so i put the cover straight back on!
in my new tank at the moment i have 2 heaters and only one cover, i noticed the other day that my royal plec had a burn on his nose, so i am going to get another cover.
i think it is really important to use these covers, expecialy with large fish which may break the heaters, loaches and fish with no scales.
sorry most of you will know this info :D