Backyard Aquaponics
A place to discuss aquaponics

There's no perfect size for fish tanks and it depends on your goals. If you are setting up an aquapoinc system, my personal recommendation is 500 gallons (1,500 liters) should be the standard to start with.

Small System vs. Big System Myths

1) 250 gallons (1,000 liters) is a big system.

This is not a big system. Only in the home aquarist hobby using artificial filtration would this become a large volume if for no other reason than tank size and space within a home. Filtration might become costly as the size increases, but really this volume is considered to be the high end of what is manageable within the home environment. As aquaponic practitioners we have to think more as aquaculturists. To the aquaculturist , 250 gallons (1,000 liters) is just a drop in the bucket.

2) My tank volume to grow bed volume ratio is what will determine the volume of my fish tank.

What should determine the volume of your fish tank is the skill level of your ability to raise fish. The lower the skill level, the bigger the tank. It should also determine the type of fish you keep, but that’s for another topic. Generally most fish utilized in aquaponic systems are hardier than store bought fish and achieve greater size, but if the tank is small, you will find yourself experiencing fish mortality and rapid water parameter swings more frequently. A small tank is a good way to learn what not to do. Therefore, buy a bigger tank initially if you can, and enter the hobby at 250 gallons (1,000 liters) or more so you can take advantage of the species available and give yourself some room to learn.

3) I can use a small system to start as a model for a bigger system when I am ready.

Big and Small systems behave very differently. For example a 10 gallon (30 liter) aquarium stocked with 1 goldfish as opposed to a 500 gallon (1,500 liter) tank stocked with 50 tilapia will have less resistance to rapid changes in water quality, temperature, and lethal levels of nitrate and ammonia buildup. The impact on one fish in a confined 10 gallon (30 liter) space is greater because no buffer capacity exists beyond the 10 gallons (30 liters). This means water quality changes occur with greater frequency, intensity, and suddenness than the larger tank with 50 fish. The smaller the system, the more frequent you will be changing water, monitoring ammonia and nitrates, and watching fish for changes in behavior. The larger the system, the less you will be doing all of the above, but checking only to ensure water stabilization. Additionally, people using smaller systems tend to use store bought fish that have less resistance to rapid water quality changes than the aquaculture species, and therefore present a more fragile equation overall.

4) If I have a large fish tank I must have enough grow bed volume to filter it.

Stocking density determines filter needs, not tank volume. If you have a large tank and no fish, you would have no reason to filter the water. The more fish you add, the more you have to filter. If you have a large tank and few fish, you may not achieve an ideal level of nutrient rich water, but you will not have to provide a lot of grow bed space either to get the water filtered, and you could always keep the large tank at a lower level to achieve greater emulsion levels. Aquaponic practitioners are always trying to determine where the balance between stocking density and maximum plant growth lies. As you add fish and experience, you can add grow space. It’s much easier to build a system that you can expand than to tear down a small system to build a bigger one.

MF, I’ll start with “ I don’t disagree with what you have said”, infact starting with a small (200l tank) I am now in the process of calculating what I can salvage from it to make the step up to 1,500l (330g) setup.

One point that has bugged me is whilst cycling, water changes can be up to 50% to keep ammonia/nitrite levels acceptable, being under severe drought conditions in Oz, tossing out 700 litres is not acceptable.

So let’s take this one step further, what I now understand is that I could have started with 10 goldies (small), a 1,500l tank and a grow bed and it would have cycled okay with minimal water volume change in comparison to the 1,500l – by adding more fish and more grow bed area over time, I can gradually build my system up and there is no need to keep recycling? In thinking this, am I on the right track?

I would like to add that originally I wanted to make sure AP was viable for me and I wasn’t prepared to have a large white elephant sitting in my backyard, so went for the smaller option.

Ell

excellent MF

Yes you are on the right track. Remember you will have to recover water that evaporates in a bigger system, and over time depending on your water source, you will have to changeout water as it gets too hard coming from the tap. I use about 200 liters per week for my system.



As many of us have...I found the small systems a way to get my head around the concept. Glad to hear you use the word "originally", you've become a scientist..hehe

You have bacteria to seed a bigger system with as well Ell, using seed bacteria from my mini systems I didn't need to change out any water when I put 20 goldies in the fish tank, after I added the 50 perch I changed out a total of 300ltrs? (75 gallons) in two days, and the system is done. Not sure I needed that much of a change out but I was also adjusting ph. I'm keeping the water from my change out and using it back in the system as I need makeup.
Nice write up MF.

Thanks Jaymie and John..

You go ell you're onto it. Keep all your water and cycle up.

I cycled 600 litres and didn't remove any but then the pond lifted in the storm... lost 200 litres tht needed replacing.

What I'm getting at, for aussies, no water changes cycling 600 litres merely by taking it very slow at first and adding bacteria and small system water.

You can go big and not tip out your water. Just add fish slow, pain in the ass though if they ship em by the hundred...

MF i think that post was great and it should be added to the faq

thanks all, the good thing about a hundred fingerlings is they are small (originally)

exactly ell, and that's lucky considering the quantities we are expected to purchase in ie, my system would have crashed and burned in 2 seconds had my barra not been tiny. And go for it with the old water into the new system. I had stuff to put into my biofilter and my water for the barra, and I was cycled in no time, with only about 250 litres changed out. AP rocks, when little fish become big, just add more grow beds!

I like the old saying (ok maybe a saying from the 80's isn't old) "nothing succeeds like excess". I've been watching the various topics, searching the web and reading lots of really thick books :schock: and as far as I can see I can make a reasonable size system work (may be a few dead fish but I'll keep trying)

I'm thinking about using ammonium chloride to get my system started before I add the fish (see http://badmanstropicalfish.com/articles/article14.html). I'm also considering purchasing a bottle of the commercial bacteria I've seen advertised for setting up biological filters (Nitrosomonas and Nitrobacter cultures for biofilters). With care and lots of water tests (and some luck ) I'll be able to get part of the cycling done before the fish hit the water.

As an aside has anyone tried this start the cycle before the fish arrive approach (I suppose in a way it's the same as adding bacteria from an old system), which I'm hopefull will save some of the water changes


Just my 5 cents worth (was 2 cents but I've rounded up like the supermarkets)

I can certainly empathise with the problems of lots of fish in a small tank. Before we bought our mega bin (780 litres), we had 44 Jade Perch in a 150 litre tub........twice daily water tests, daily water changes and enough air to refloat the Titanic.

We plan to use our current mega bin arrangement as a nursery system - for rearing fish up to about 4 months and then we'll move them to some thing larger......maybe 3,000 litres or more. This way, we plan to increase the number of fish we can turn over each year.

Yea Baby! Crank up the volume.

Eame - I think that fishless cycling is certainly worth a go. Your link didn't work for me. Here is another link that discusses it briefly Fishless cycling.

One of the problems is finding a pure source of ammonia.

I've found one of the major reasons why we are going with a big tank, 10000L as a start up tank. When I first joined this forum I carefully read everything here, jumped in and started posting almost immediately with some of the rubbish that I'm sure you've come to recognise.

Anyway, one of the first things I read was on the Portal Page of the forum and reads as follows:

"Steve's To Do list for starting a system

Posted on 08-15-2006 03:00:17 pm by steve
Hi to all the new members!

I thought i'd make a short to do list on what i did when first starting my system. I believe it is a very simple guide to get an aquaponics system up and running but more importantly CYCLED and STABLE

Don't stress too much about the ifs and buts, just do it


IMHO do this:


A) Get a container for a fishtank that is as large as you possibly can.

B) ... "


I took this to heart, for many reasons, mainly cos I like to start big, hopefully not crash and burn, and continue. Other reasons include, the larger water volume allowing for heat sink, chemical changes are slower, etc

Anyway, in two weeks or so, my monster tank will finally get water in it, and then in a month the fish will arrive.

"Newbies" need to go with what they can afford and are comfortable working and living with. Life is an experience and we only learn from living it.