I recently bought an Eheim 2126 which has a built in heater but in hindsight it appears that others are probably just as good for the money. I had a look at the Hydor and Tetratec models and both look well built and probably better value than the Eheim but I suppose time will tell. I could get the Hydor Prime 20 or the Tetratec EX700 plus the new Hydor external heater for around £90 as opposed to the £140 plus media I paid for the Eheim. I notice that the Tetratec also has a 3 year warranty (same as Eheim). Annoyingly I also had to splash out another £28 or something to get a more discrete intake/spraybar/hoses (went for the installation kit 1, 2 in grey and JBL clear hoses) as the green stuck out too much in the tank. If I set up another tank, I think I will try the Tetratec/Hydor external heater combo.