Fluval E 300w Advanced Electronic Heater

[SPH71]

I have just purchased the Fluval 300w E Series heater. I have a 260L tank and have been informed that this particular heater should be placed diagonally, on reading a forum post, this was placed horizontally. I understand that I require a good flow of water in close proximity of the heater, but would anyone be able to confirm the best heater orientation please. Diagonal or Horizontal?

 

[earhtmother]

I would think that horizontal would be ok. I *think* the reason for diagonal is to ensure that there is not a *hot spot* created. Personally I always use 2 heaters in any tank larger than 30g/115L just to prevent any frozen/boiled fish in the event of a heater failure.