Backyard Aquaponics
A place to discuss aquaponics

After having read through quite a few posts here I've decided to have a crack at setting up my own system. At this stage I'm still getting all my ideas together, and I would welcome any comments other members might have to offer

Currently I am thinking of setting up a small outdoor system based around a 200 litre glass aquarium (standard 4ft - closer to 175 litres really) that I currently have spare. As it would be a small system I would like to use as much water volume as possible, so I plan on using a sump. The sump will most likely be a 100 litre plastic (PP 05) storage container I have laying around.

I have not decided what I'll use as a grow bed just yet. I'm guessing I'll just use a plastic fish tub or similar plastic container that is somewhere around 200-300mm deep, and has an approx volume capacity of 3/4 of the sump (or thereabouts - I know displacement comes into it, just havent done the calcs. ).

The build for my idea is as follows:


Excuse the sketch - not to scale, new to sketchup. Plumbing not shown either.

For ease of sake of setting this up in my backyard, I thought of having the fishtank slightly elevated so it was just higher than the sump. Basically it sits on a concrete block stand to allow enough of a height difference to use a simple overflow box between the tank and the sump. Water from the tank goes through the overflow to the sump, where it is then pumped up to the grow bed.

The grow medium will most likely be approx. 10mm gravel, as I can source it fairly cheaply. To drain the grow bed I intend on using what I've seen refered to on the forum as a "bell siphon". This can empty directly into the fish tank as the grow bed is partially over it.

So, basically water will be continually pumped from the sump to the grow bed, which will (hopefully) fill then drain to the fishtank, which will then overflow to the sump etc etc etc....

I know it would be desireable to have the tank overflow directly to the grow-bed, however to do that I will need to have the tank and bed at the same level (or the tank higher), which would require more engineering and materials on my part, and would aslo be harder to set up. I really did like the idea of keeping the water level in the fish tank constant, which is why I'm using the sump and not pumping directly from the tank.

Plumbing will be made from standard pvc piping and fittings.

Pump is a spare I have from my aquarium gear. Can't remember the brand, but it's rated at 1200 or 1400 litres with a 1.8m head (I think).

As far as plants and fish are concerned, I thought this little project would make a nice herb garden for my kitchen. Seeing as we are going into winter and it's a smaller system I thought I'd just start of with some goldish.

So, any comments?

Apart from general feedback, I suppose I'm wondering:

1) Is this feasable?
2) Any recomendations on use of plastic? I know there's probably endless debate over whats safe or not.. But I have been
watching those 500litre green tanks from Bunnings for a while now...
3) Instead of cycling with goldies etc, does anyone use a fishless cycle (adding ammonia), or is it too tricky/slow on a
larger scale?
4) How well do people cover thier systems? I realise it would be good to keep the birds and cats out, but is shade or a
greenhouse recommended? In regards to temp. also?

I'm sure Ive got loads more, but Im currently at work , so I'll post in dribs and drabs.

Cheers!

Shade cloth is used to keep water temp fluctuations down, keep fish from jumping out, and hopefully keep critters from getting to the fish. Looks like you've done some research and got some parts to work with, good luck!

Hi Baron
make sure you can add another grow bed as your fish get bigger and produce more waste you will need the space to plant more to remove the nitrates ( or change the choice of plants to remove more nitrates )

i have 4 growbeds and nft pipe attached to my 200 ltr system and not enough growbed space for what i want to plant either

growbeds measure 50cm length 35cm wide and 25cm deep

im probably near the other end of the scale where i have no problem removing all of the nitrates from the system and more especially when i have things like tomatoes in the system ( i have been supplementing ammonia in the system with urea to cope until my fish get bigger ( and they have doubled in size since i have put them in )

good luck with your system

Thanks for the replies guys

I'm used to heavily planted aquaria with high efficiency canister filters, so the idea of using grow beds as the filter (while not disimilar to under-gravel filters) is a little different to what Im used to. Obviously its all still the nitrogen cycle, but the size of the filter is just on a larger scale.

I've since done a bit more reading on the ratios of beds to tanks, along with displacement ratios. If we assume I'm going to have roughly 40% water in a flooded growbed, obviously I can still have a fairly large growing area relative to the size of my system.... larger than I first thought, anyway

Just quickly on growing bed medium... I've seen a couple of posts talking about pros and cons of various materials, however final choice can be heavily swayed by cost. My local supplier of landscaping materials has many forms of gravel (graded sizes and types), but they also have red scoria (14mm). They do the gravel and scoria in your average 20kg sized bag for the same price, so seeing as the cost is the same, I was wondering what people would recommend - pea gravel or scoria?

I can tell you the limestone bedrock I'm using has hindered my system. It has kept the pH over 7.6 and my sprouts never got passed the sprout stage. The plants all stayed green but just haven't grown anymore. I think some just gave up trying and died (maybe root rot), the rest are still green. Except for the ivy clippings, after a couple weeks they developed new roots and are doing just fine, they must not care about a higher pH like vegetables do. (and the ivy's roots are directly in the fish tank)