Simply Koi and More Koi

Well I've enjoyed the thread and it's helped me decide what to do. I've bought 3 new 300w aquarium heaters and I'm going to install them inside my Nexus filter. The idea is not to heat the pond to a fixed temp, but rather to stop the temp falling below a certain point. My pond is currently sitting at 7.5 degrees and the fish are eating (Tetra wheatgerm) I figure that it shouldn't be too difficult to raise the temp to 10 - 12 degrees and maintain it.
Particularly interested in B. Scotts post about "Aeromonas Alley" and think that a good compromise would be to try and maintain a temp of around 11 - 11.5 degrees.
The comment from Mnementh about having a dedicated power supply has also pushed me in the direction of multiple smaller wattage heaters. I've already spent (Over spent) a small fortune on this new pond and don't want to spend any more than is absolutely necessary. Will keep you all posted on the success of these aquarium heaters. I'm actually quite optimistic!! Thanks for all your input!!

Hi Louie
I hope I am wrong for your electric bills sake, but most aquarium heaters can be set no lower than 16 degrees and I fear that as 900 watts is not enough for 2000 gallons they will be on 24/7. An equilavent 3KW heater would use roughly the same amount of electric if on for just over 7 hrs in any 24 which is highly unlikely. Mine is set at 12 degrees on 2200 gallons and only comes on at 11.8 (Filtertech Pond Controller). It only takes 10-15 mins of heat to go back to 12 and then the heater is off again for a couple of hours till the temp falls again.

Shaun

Add to the fact that aquarium heaters are glass and prone to break. Biggest danger is a drop in water levels (cleaning filter?) and when the water hits em again they go pop! If they go while in the pond you could give the fish quite a jolt.
If nothing else try to get a heater with a solid mantel!

B.Scott

Well I've decided to give it a go anyway. Got hold of three new 300 watt heaters from Ebay and have put them in the Pod well below the waterline. Will run them for 24 hours initially to see what effect they have (if any) and then start playing around with timings to try and optimise their output.
Shaun was right about the thermostat settings!! Lowest temp on these is 18 degrees! But at a total cost of only £30 I can afford to try it out. If the worst comes to the worst I can always bin the idea and use the heaters for any QT needs that might arise in the future or maybe for growing on fry if I ever try that.
I know that the proper road to go down would be the 3kw Elecro running off a dedicated high ampage circuit, but I honestly can't afford the heater or the sparky, so this is a cheap alternative to stop the fish freezing should the weather become really bad. And if I can up the ambient water temp by a couple of degrees without it costing an arm and a leg then surely it can only help?! Fingers Crossed!!