Im running a 3kw heater on my 500gallon qt unfortunately i cant control the temp very well. The thermostat was set at 18 dgrees but the pond was running at 22 degrees, ive now turned it down to 12degrees on the thermostat and the pond is still running at 20-22degrees? Im guessing its just way to big for my tank?
Would a 500 watt aquarium heater be man enough for the job? Would also mean i could wire it in easier to the electrics to the pond as the 3kw is a bit beefy?
I would use 3 x 500w aquarium heaters placed inside a piece of 2 inch pipe for each heater with holes drilled into it to allow for the heated to water to escape more effiicently. Your 3kw heater should run at the set temperature if it isn't I would turn it off as this sounds faulty.
You could get away with 2 x heaters but by using 3 your tem control is easier to manage and not on for so long.
Jules
p.s. I am over your way this week doing a Pergola for some lucky chap hope you have good weather that side of the river?
That sounds like a plan, will pick some heaters up this week and get the 3kw heater off the pond. Where is the best place for the heaters in the pond, do they need to be in the flow?
The weather is always good in sunny Essex, id just bring a umbrella to be safe? Any idea when you will be at Trevors?
Well when i had one in there on its own somehow one got smashed I was looking in the tank and i thought what that on the bottom and when netted it was part of the glass tube so i pulled out the heater and sure enough it was broken.
I though i don't want that to happen again so i then installed the pipe and put the heaters in the pipe
I have 2 300w heaters heating my 10,000 litre pond, they kept it above 8C all winter and have got it up to 14 currently,
Didnt plan on them heating it, just stuck em in to stop the waterfall from freezing and to keep a little warmth in the K1, but have worked much better than expected
so should easily do yours
With 3KW in there it must have been more like an electric kettle than a warm bath
On the basis that you need to be able to control the heat in a QT whatever the outside temp think that you need 1kw in 500gallons . With 1000gallons i needed 2kw to be able to maintain comfortably at 25 through the winter inside; 1kw was struggling. No problem now since moving to gas; save to check the probe is in the tank!
Have you got a polycarb cover over the tank? When I leave mine on the air temp in the shed hit a minimum of 10 overnight in the winter, when I take it off min air temp was 13.
Personally think that an in line heater is more efficent than aquarium types, need to ciculate the heat from the heater element.
Hi Madmole
Been a while since I did thermo dynamics and not sure what your ambient temps have been like in sunny Kent, but if your heaters are actually only consuming 300w a piece and are heating that volume of water as you describe then you are onto a winner!
Well in Surrey, but yes they kept the pond at 8C when it was -5 at night
Just floated some bubble wrap over most of the pond on the worst nights, Waterfall and all air still on. However the pond is all in ground and I put a lot of Underlay and carpet under the liner. Filters and all plumbing are inside an insulated filter house. With the heat from the 48W UV and the 2 in pond pumps, the filter house stayed at >12 inside all winter
I put the heaters in to stop the waterfall freezing and keep some bacteri active in the filter and have been very suprised at how warm its kept. Didnt pkan it as actual heating. But has meant I have been able to feed all winter and fish have been active and healthy
Sorry for delay. My growing on pond is totally enclosed with a twin wood wall with a small amount of insulation in between with a four wall polycarb roof. The filter bay is enclosed but is not yet insulated as still trying to get it layed out neatly.
I bought a 500 watt heater this week and have now switched off the 3kw, so far it has just about held the temp to 19 degrees but is on constantly, ive just ordered a second one to help in the colder weather.
The 3kw heater was not as far out as i had thought-my two thermometers read at least 2 degrees out from each other! Can any one recomend a digital thermometer that is accurate? Ive been looking at the ones from monitor direct which are remote
hope you have good weather that side of the river? 
