Backyard Aquaponics
A place to discuss aquaponics

It's starting to get colder here Melbourne and it's time to think about something too take some of the chill off the water.

I know that not being able to fully enclose the FT in a structure anything I do will be an uphill battle, but I'd like to do the best I can for as little cost as possible, HOW MANY TIMES HAVE YOU HEARD THAT?

Researching alternatives I've come across an efficient aquarium heater that uses only 300 watts and supposedly will heat up to 1,000 litres.

Their data sheet mentions 600 litres & 1,000 litres with temperatures from 18.0°C to 34.0°C, even at 18.0°C that would be far better than what I can expect from just tank insulation and 300 watts wouldn't break the bank.

24/7 it would send the power bill up but on a timer just running overnight with the main objective too keep the fish feeding in the morning and keep their growth up, anything would be better than where I'm at now.

It may not run off a timer some Variac’s & Dimmers won't run on a timer.

Has anyone used this brand of heater and are their claims anywhere near what they state? or do you have any better advice on CHEAP HEATING.

https://www.eheim.com/en_GB/products/te ... h=1000%20l

I live in Spokane WA and believe you me it gets REALLY cold here. I built one of these

https://www.youtube.com/watch?v=QWZ3qQ3R8_A

It cost about $50 to build and it does what I need. I am planing to build another one but I am trying to heat 4000 liters. I have not kept track of its power usage though.

Hope this helps.

300W will heat 1000l of water by one degree in about 4 hours, assuming no losses. By the sound of it, you have significant losses, so it may well need to be run for much of the day and night to keep up with heat loss from the system in winter.

Run the 300W heater for 24 hours and measure your water temperature at the start and end, and you can calculate how much energy was lost during that period.
For example, lets say you started at 15C, and 24 hours later it was 19C, then we know the useful energy retained was 16720kJ, or 4.64kWh. You put 7.2kWh into the system via a continuous heating rate of 300W, so the system has lost 2.56kWh or ~9200kJ, via convection, conduction, and some radiation. The aim is to minimise the losses, in order to minimise the cost of running the system. Of course, solar heating is free to run, but there is a significant set-up cost.
Heat pumps are much more than 100% effficient, but the cost of one for a small system would never be recovered by the savings, especially if you insulate the system well.

Using your 300W heating element and heavily insulating the FT (including a top cover) and GBs to reduce ongoing energy cost would be the way to go IMO.

aboman I've been aware of your heater for quite awhile and think you've done a great job with it and I gave it some thought.

I don't have access to the machinery too build anything like it and Insurance wise in Australia if anything went wrong they would nail you too the wall.

Anything electrical needs to be approved before in comes into the country and therefore ticks all the boxes insurance wise.


Gunagulla that's what I thought, currently I have very cheap power but that runs out in December, so now is the time to test and see what happens and I'm only trying too keep my Silver Perch growing a little through winter against not growing any at all.

I can afford to run power 24/7 up until December and that is well beyond the time I need too run it, I'll turn the pump off at night and see how I get on.

I've found that heater is quite cheap at $62.00 AUD delivered on ebay
http://www.ebay.com.au/itm/Eheim-Thermo ... 3f318ed953


Guys thanks for your support.

The thermostat should ensure if doesn't run any longer than necessary, just set the temp a bit below the temp it gets to naturally in the day, and it might barely come on in daylight hours, except in cold overcast weather... not that you get much of that in Melbourne

really you should know better Joblow

Sure you can build a cheap heater but you still have to power the thing and 300w is going to do stuff all.

As G said four hours to raise the temp one degree assuming no losses. So yeah it will work, if the temperature outside is 12c you might have a chance of keeping it elevated to 12.5C but 12.25C is more likely.

yeah what stuart said, I ran two 300 waters last winter they made S.F.A. diference to the temp in the IBC system, but did add a couple of hundred to the next power bill.

The black poly coils were far more effective for me last year I ran a pond pump drawing 40 watts from 10 am till 5 pm, sucking water from the sump pushing it through the coil and back to the FT. (only works when the suns out though)

How long was the poly?

What diameter?

System (1) 1 X 25mm coil X about 50M (Runs of pump in sump tank)
+ 13mm coil about 75M running off line split of main pump.

System (2) 13mm X 75M coil also split off main pump outlet.

as per pics on my IBC AP thread.

Hi Stuart,

I was expecting a chastise from you and would have been disappointed if it didn't happen

In my defense I was impressed or sucked in by the product specifications, Stuart the manufacturer wouldn't lie too me would they?

Their specs say it will heat a 1,000 litres to 18°C - 34°C so I was hoping to just take the chill off the water but always thought that throwing the dregs from my morning cup of coffee in the FT would have about the same effect. I know that it's more about the loss of heat rather than the gain.



Blind Freddie,

I saw your black poly setup on your thread a while back and had forgotten about it.

That's the way I will go, I'm at two minds as to which way to go, use the split I have already in the sump and run it continuously 24/7 with the option of turning the pump off on cold nights, or running a second pump 8.00am - 5.00pm on a timer. The first option saves power as is probably the better way too go.

Blind Freddie I think I will build a flat tray 50mm - 90mm high, painted black inside with a glass top and put the black poly coil in there, the glass and black paint will all help.

I'm not sure what temperature this water would be going into the FT on hot days and maybe it does need to be run from a second pump after all, then that pump is just not turned on warmer days. Winter in Melbourne the warmer days are not going to be a problem but I'd hate too be away from home and the day turned hot.

I like Gunagulla's Pex-Al-Pex idea but that's too expensive for my budget, I don't know if the black poly would work in the same situation, on a buried FT it would OK but with an IBC forget it, all those 90° elbows, 4 every time the tube went around the tank, so Blind Freddie I'm back with you mate.

Thanks for your input guys.

You are wasting your time and money
A bit like trying to push a ball up a hill with a pointy stick

I'm starting to get that message loud and clear, so it might be Trout next year when I get these guys through.

I plan on insulating my 4500L tank.. wrap it in fiberglass ceiling batts then clad it so it looks decent.. And find a cheap pool heater that runs water thru a black rubber snake of pipe on the roof.

Do you know any plumbers? A mate of mine keeps his 1000L spa at around 40 deg all Winter here in SA using an old solar hot water system panel. You need to be able to control the heating and cooling cycle though as it will turn into a chiller on cold days and definitely at night if you're not careful. He uses a thermocouple in both the spa and the solar collector and an Arduino microprocessor to turn a pump on and off when the temperature difference is in his favour. Sounds a little high tech, but the Arduino system is actually not too hard to pick up if you've got the time to learn it. He uses it as a cooler in Summer as he needs to cycle the water slightly in Summer to stop the water boiling during the day and hence overshoots his ideal temp. A sheet of cladding over the collector will stop most of these issues though. I'll probably do something similar if I decide to grow barra, but at this stage my system is two empty tanks and my Arduino use is limited to an automated brewery!! If I ever get my system off the ground I'll make sure I post the code, but I'm sure someone else out there has done it already.

Good luck.


@ Stuart - It's good to see some engineering calcs kicking around the forum. It brings back the old thermodynamic days!!