Backyard Aquaponics
A place to discuss aquaponics

hi everyone,
im currently designing an Aquaponics system out of an ibc container, a header tank, two bell siphons, and a pump on a float switch or timer, to save power.

basically the pump will fill up the header tank and switch off, then the bell siphon floods the grow bed, triggering the grow bed bell siphon and the cycle begins again.

In the true spirit of permaculture i want to have the system as fully self sufficient as possible.

my idea is to hook up solar panels (1 or 2) to a couple of deep cycle batteries which will run the pump and an auto-feeder. the panels should be able to charge one battery while the other is running the pump

my problem is that im not sure how to go about this, and im really hoping that someone can give me a hand designing the system and choosing the components or lead me in the right direction of where to find info on how to create this kind of system

any help would be greatly appreciated.
Cheers, Sam

Good to see a new inventor!!!!

this topic has been covered many times and everyone has their own ideas, all i can say is Experiment, Experiment, Experiment.

a few things i would Implement, Low Voltage pumps dont last long, i would get yourself a small 3000 l/ph Pump that avg 65w, and a small inverter 150w should be ok. this will be cheaper than finding the 12v pump dies after 3 weeks.

you wouldnt need the 2nd Bell Siphon, run the Growbed as a Timed Flood and Drain setup so the header tank overflows into the Growbed and then the growbed empties over 45min slowly.

also with this setup if you find the solar doesnt do the job, you can top it up with mains power as needed.

Now all that said if you look at this side of it all;

a 60w pump running 15/45 (15 on 45 off in the hour) over an hour only uses 15 watts .0015 KW/H per hour 0.36kw/h per day 131 Kw/h per year.

Take into consideration the Cost of Battery, Solar panels, The Replacement of battery, the toll on the environment and miles used to get those items to your house and disposal of batteries.

does this outweigh the use of 131 kw/h of mains per year??

i would use the money to put a grid system on your house instead of Buying Batteries, Panels and things to run an AP system.

you wouldnt need a headertank or anything either, Pump in the FT, straight to the growbed/s and thats it, less plumbing, less things to go wrong

Wish I could help with the techno mumbo jumbo but I can't What I can tell you is that others have looked at going for a 100% stand alone solar powerd set up and after crunching the numbers they generally conclude that the payback time is too long to be ecconomical when you factor the cost of the set up and the life of the componants. This is because there are no government subsidies for a small stand alone solar set up, so at this stage grid electricity is cheaper and easier.

If you want to be carbon neutral in your AP setup and you can afford it, a more ecconomical solution would be a small grid connected solar setup that are subsidised by the government to make them cheaper, you draw power from a semi reliable grid for your system but pump power back into it when you can. Some states even have very attractive feed in tarifs, again subsidised by the government, so that you may even be selling your peak power electricity back to the grid for more then you are buying it for at other times of the day.

thanks jamey and simo,

ive also been directed to a Savonius rotor windmill
(http://www.linux-host.org/energy/asavonius.html) to provide the charge for the batteries,
while an interesting idea it could solve the problem of the solar cells not charging at night, and when used in tandem with a solar cell i think i should be covered for the batteries,

in terms of the environmental toll, im trying to use all recycled materials possibly second hand batteries, (though im not sure this is a good idea because of reduced battery life), salvaged circuit components from various old electrical devices (VCR's some kitchen appliances and computers)

Simo, ive done some preliminary number crunching and ive calculated the cost of a very small experimental system to be under about $750, not cheap, but a price im willing to pay for a ongoing experiment in sustainability

one last thing, im still torn on the inverter. i know that the pumps may be a better quality but
the system will be implemented on my grandparents farm in kyneton and i would prefer to keep everything rated below 50 Volts

Its Not Quality, its reliability and replacement, one thing i will suggest when looking for a pump, Ask around, possibliy a marine boat shop to find something that will stand up to the job.

Iv done a search in my catelog for pumps that are low voltage, the only ones i can see are Aquapro Low voltage pond pumps.

200lph, 500lph and 750lph as you can see the Head height is next to nothing.


as an electronics enthusiast since i was 6 and working as a commercial automatic gate tech for years, also working with solar gate operators etc, smaller domestic gate systems that were solar were a nightmare, and our commercial solar gate setups used inverters to run More efficient mains powered motors, but even then the batteries needed replacing frequently.

thanks guys for your interest and opinions, much appreciated

Ive been looking into marine pumps and it looks like i might go for a bilge pump, a decent one lasts bloody ages! my dad has some on his boat and they still run like new even though they're about 12 years old... this may be because they aren't used very much but it is a promising sign none the less, another bonus is they are 12V,.

As an electrician turned robotics engineering student, i think i should be able to cobble something together and the point of keeping it extra low voltage (0-50V), aside from the safety factor, is so anyone can work on the system without holding an electrical licence (at least in victoria anyway).

i understand the cost of the panel and control system may far outweigh the benefits, however this project is really something i can cut my teeth on and start to dabble into the finer arts of sustainable living and renewable energy.

in addition to the solar panel i am looking into vertical axis wind turbines or savonius rotors hooked up to a generator and the solar panels, and also a scaled down conventional windmill driving a small pump to fill the header tank...

these ideas will always require fine tuning and tweaking to ensure efficiency and i am by no means saying that these "contraptions" i intend to butcher together will run at a high efficiency, rather i want to prove to myself that these ideas can perform at a small scale and could be implemented on a larger system.

The major problem i have is, i want to implement this system on a little farm in kyenton,
a friend and I are going to build a little greenhouse out of some timber lying around and some salvaged greenhouse plastic from an old greenhouse on the property. Not the problem.... the issue comes from the distinct lack of powerpoints in the garden where we are going to build the greenhouse... while i could run power to the garden, its a little impractical because of the upgraded cable needed and the 50m trench i would have to dig through decomposed granite just to lay the cable. so it aint gonna happen!

in terms of food for the system, i intend to try a vermiponics setup to grow duckweed and some as yet undecided plant that the fish could eat... this is all very exciting at the moment and i cant wait to get started and run some tests...

So, this weekend im actually getting my arse into gear and im going to build a small savonius rotor and hook it up to an old vcr motor ive got lying around, i know its a bit of a "hit and hope" strategy but meh, ive gotta start somewhere, ill keep everyone posted as to how that goes

Cheers, Sam

i get that the collector batteries may not last long and 230V rated motors may run more efficiently but i think an addition of a mechanical windmill driving a pump may provide the solution i am looking for. in such a system the electric pump would only run when the windmill isnt running, this could be achieved by installing an sensor on the windmill shaft which indicates if the shaft is rotating/pumping fast enough and reacts accordingly.

of course this is all speculation at the moment and i wont really know how this will all work unless i get out there and do it. so wish me luck and ill let you know how i go

I admire your intentions Samwise... and good luck....

However I have to point out that the critical factor in any aquaponics system ...

Is maintaining a near constant level of dissolved oxygen... to keep your fish alive...

How much air you'll need.. will depend on how many fish you stock, and how big you grow them...

How many fish you can stock... depends on the amount of filtration you have...

And the filtration component, and even feed conversion both have an oxygen overhead....

I'm not sure that you have factored oxygenation into your equations... or the ramifications of failure of any power supply, especially overnight... in relation to supply of oxygenation...

In solar trials that BYAP did ... they found it difficult to maintain a system with a 1000L fish tank, and two 500L grow beds.... with anything less than a 60w solar panel...

There goes your $750 budget... on the solar panel alone...

hi rupert,

i did sort of take into account the dissolved oxygen as I figured it can be created when the grow bed drains, as long as there is flowing water the fish should be alright.

as for the budget.... well i knew it wasnt going to last long but im sure i will still find some way to fund it

as it is, i suppose i wont know until i actually build and test some of the components
however i will take in everything you have said, i really do appreciate the interest

Just keep your priorities sorted. It might be very possible to create an aquaponics system that functions with a solar system in your budget if that is your priority as long as that is the priority. If you also expect it to provide x amount of fish per week and do it while also being fed on worms and duckweed that you also grow on site while not actually being there to do the monitoring, well that is getting unrealistic.

If doing a solar powered system is the priority you will probably be running a very small system with very few fish. A slow flow of water may not provide enough aeration for a heavy load of fish when the weather gets warm and I know people who have lost an entire tank of fish even in the shade just because the air pump got unplugged and they didn't think they were stocked that heavily. You will have to experiment to see how much your system can support.

As to the header tank idea. I don't think it will really save you anything if you are also hoping to turn off the pump. The header tank is meant for a situation where you want fast fill, slow drain but the pump is not strong enough to provide that so must run full time and use a header tank. The extra height involved in lifting water to a header tank will also require more power for the same or less flow. So do some math carefully with head heights and such to see what will be most energy efficient for the same flows. Running the pump on a timer to the grow beds may be far simpler and more energy efficient if you will be turning the pump on and off anyway. Making a little picaxe repeat cycle timer to control a 12 volt pump should be really simple if you are up for building your own solar charge controller out of old appliance parts.

Cheapest energie is the unused energy!

The make an energie efficient aquaponic system you need to reduce power usage. To achive this you have to look after your pump first, because thats the biggest consumer (at least 80%). The pumps efficeincy inverse proportional to the square of the lifting height. This means your pump pumps more water from the same energy if it has lower lifting height.

Bottom line you have to design a system where you minimise the lifting heights, to save energy.

- Header tank is a waste of energy
- Forget solar panels and battries, with te current energie prizes they will newer return investment.

1. Build timed system of a FT under and GBs ower it, probably thats the most energy efficient. This way water lifting height is around 50cms.
+ easy to build
+ efficient to run
- water level is not constans for fish, fish not happy
- pump is in the FT so you have to clean it regularly


2. Build a CHIFT PIST timed or siphon. Minium lifting heightis arrond 70cm.
- more parts, tanks, pipes, more money
- less energie efficient
+ costant water level in FT, no pump in FT, fish are happy
+ pump in sump tank stays relatively clean