Backyard Aquaponics
A place to discuss aquaponics

hi everyone I am an established aquarist and gardener and am about to take the leap and start my own aquaponics system.
Now I have a 22000 litre poly tank which I plan on cutting down to 8-11000 litres and my issues are as follows;

1) I'm not sure how big my planter beds will need to be ( was thinking 2 poly 44 gallon drums cut down the guts).

2) stocking. I would like to have a total of about 75 fish eventually but was going to start with 25 fingerlings (silver perch) but im unsure of cycling times and initial stocking amounts.

3)pump capacicty. If im running a 10000 litre system with only 75 silver perch total (or less) I would think that a 10000 lph pump would be sufficient?

4)cycling. as mentioned above im unsure of cycling in huge volumes of water like this so I would love a rundown of it ( if its the same as a regular fish tank I can handle that without help).

ANY help or feedback will be muchly appreciated

here are a few pics of the tank ( its already in location) exuse the fire pile in the corner

Im planning on putting up metal framework for the planters to the left of the tank and having the pump in the shed with the in/out feeds going through the wall.

With the fish, you'll need to still stock to your filtration levels. Which for 2 drums will work out to about 10 fish.

I'd be thinking bigger with grow beds, you can make bigger ones easily enough, or get some IBC's and chop them up.

It might be slightly different for a larger water volume, but it's still far safer to stick to 1 fish per 20-25L of wet media ratios.

With the pump, I remember a fancy excel document, where you put in your maximum stocking capacity, water volume and it recommends a pump size. I can't find it for the life of me. But for 2 drums, the 10,000L pump will be massive overkill.

Cycling can be done several ways, throw a dead fish in, add some sacrifical goldfish, add all the fish and don't feed much until the nitrates start showing up, put in some charlie carp fish emulsion.

Have a look through the IBC of aquaponics at the top of the page, it has all the information there.

I would leave the 22,000L tank as it is, maybe sell it if you can't use it for anything else, and use the money to buy a smaller FT or two.

Blue 205L drums cut lengthways, you will need about 20 to 25 of them for 75 Silver perch.

thanks for the replies, this is why I thought i'd ask before attempting as I have only just in the last week stumbled upon aquaponics on a larger scale.
I may just have to scale down the tank size a little and scale up my grow bed size lol.
realistically I would like at least 50 perch in there as I am starting this to be more self sufficient (obviously will be starting off with less fish), so may just end up cutting the tank down anyway but making it a little shallower.
as for the beds I may haven to get my hands on a second hand 1500-2000 litre slimline tank to cut down vertically so I can come closer to my stocking requirements.
will do a few more weeks (or months) of research (and saving) and as soon as I start the build I willstart a new thread

or could make a stand and use the top of the tank as a huge planter bed haha maybe not but would certainly be big enough

It should make a fine grow bed, the top of it, as long as the plastic can handle the weight.

I had the same worries about hacking up a tank, with it's structural integrity, but others had done it.

I wouldn't use it whole though, you wouldn't be able to check the fish, and it'd be too dark to see them. And catching them would be interesting too.

If you're handy at building stuff, look at Ryan's thread. It's a pretty simple method to make some grow beds.

I'll buy your tank...if you can deliver it to me. lol

Do a search for PJ's system over in west Aussie as he used a big concrete tank, I cut down a 4000 litre tank for my fish tank. Is 1800 dia x 1800 high and if you are cutting a tank down you will then have to run a strap around the outside other wise there is a chance of it splitting from the weight of water.

Start smaller and get the experience first, I also have half a 22000 litre tank with a split I was considering welding and using but have enough trouble harvesting from my current system. Cheers

CC, what kind of strap? Metal or fiberglass banding? I thought about that with my tanks also.

Hi Chris I use the builders metal strap which is used for tension across walls and roofs. About 1 inch wide with holes positioned every few inches. There is a special fitting for drawing the strap together and thus creating the tension on the frame work.

Have not gone to the system this morning so when it stops raining will go down and take a photo and post it. Cheers

Check this page will give you an idea of it. viewtopic.php?f=18&t=14114&start=60

hey I have not had the internet for a while

A friend and I have been planning and scheming and we have decided to go ahead with the 22k litre tank idea but have a few questions still.

1) can I have this much (8-12000 litres) water and only 8 beds (ibcs cut down to make 2 30cm deep beds each container) with only about 50 to 75 fish? as most people say to use a certain volume of water per volume of planter bed and fish but I want a HUGE lightly stocked tank and each fish would end up with about 60 or more litres of planter bed ( more than twice what is recommended) so there is less temp fluctuation/ crowding issues and parameter shifts.

2) I was thinking of putting the tank inside the shed now so i have more room for the beds (and additional beds in the future) will the fish need a light source? say a fluorescent cool white tube on a 12-12 timer to simulate day light.

3) can i add additional crustaceans (fresh water shrimp and/or yabbies) with my silver perch and have them actually grow out to harvest size?

4) I would like to add a blue barrel cut in half for 2 fruit trees as additional planters, Can you have fruit trees in AP?

ANY help would e much appreciated

also construction wise we will be set because i am very handy and my friend who has become very keen to set this up is an engineer and we are getting advice on setting up the plumbing by a hydro expert so we really only need a few green lights on some questions then we will start setting up.

and question 5... i have 2 (1 spare) 3200 lph water pumps will one of these be sufficient for approx 3000l of growbed?

The old rule of thumb was to turnover the system water volume once per hour but in all honesty Ive seen many variations work. Usually pump ratings are less than what are stated and even less as they age so it sometimes pays to choose a larger pump. I think in your case you would be better off with a 6-7000lph.