Hi robbo851,
I have the rio 125 which I think is a good tank for the money. As specks says, the filter box in the corner houses the heater, pump and filter system.
The temperature has not been too bad - have only had to adjust the heater once (turned down) over the past 3 weeks, which may have something to do with the central heating kicking on in the house - here comes winter!!.
So specks - you went for the big one eh?! I was tempted but it would not quite fit where I wanted to put it.