I did a search in this forum and found a thread on heater placement for HOB filters but I was wondering where would be the best place for a submersible heater in a tank with a canister filter? Also, most photos I see of submersible heaters show it stauck to the back of the tank at an angle. Is there any particular reason for this? Can you place a submersible heater in a horizontal/flat position near the bottom of the tank? Sorry if these seem like silly questions I simply have very little experience using heaters and would appreciate any assistance.