Backyard Aquaponics
A place to discuss aquaponics

temp seems so critical for good growth of species such as jades and barra. We have been having cool nights here and my temp gets down to 21 or 22 degs, it is 25 by mid afternoon, but the cold nights are killing me.

We've been running an air conditioner for most of the day (and night) for weeks so cold nights are not an issue for us.....certainly not at this time of the year.

I think the secret to successful small-scale fish farming are small tanks. You can control the production parameters to a much greater extent than with a large tank......particularly when it comes to temperature.

It's taken a fair bit of effort to overcome my natural tendency to go big with aquaponics (or to complicate it) but I'm almost there.

Stu, have you thought about having a small tank (or two) as grow out tanks.....where you focus on getting a smaller number of fish to eating size faster.....dipping into your larger tanks as you eat the fish in the small tank(s).

Of course, as we've discussed before, if you get it wrong with a small tank....it's crying time that much quicker.

Larger bodies of water have advantages also - particularly less rapid changes in various parameters such as temperature and PH.

I agree with VB - I have what I suppose you would class as something inbetween with 2 1000L tanks connected together - but I started with 3 small tanks, which overflowed one into the other... the only advantage I found with small tanks over big ones was that it used less water. My small tanks suffered from temp fluctuation, the fish were always skittish (guess shallow water did not make them feel safe) and ph swings were sudden. With my bigger tanks the fish are slow and not afraid to come to the surface to feed, my system's temp has remained constant and my fish have grown faster (seems to be linked to the depth of the tank)...
As these 1000L tanks are neither huge or small, I would say that they are good for beginners, gives them far more stability. Also, I have a thrid one for purging and as a possible hospital tank...
When I look over the system which are comming to life and being shared on BYAP I would say that there is no hard and fast rule to what is 'best' - it all boils down to personal preferance and budget constraints

Could be interesting to see how much quicker the fish grew in a small tank that was heated to optimum temperature. Do you still have some form of heating in your big tank or the vat system Stu?

I equate aquaponics with food production.....so (for me) that rules out goldfish and tanks that are unable/unlikely to produce food.

I know others will see it differently......and that's fine.

When I refer to small tanks, I'm thinking of anything up around the 1000 litre mark.

I run a tank that holds about 650 litres of water and I can control the temperature and pH much more precisely......and much more cost effectively....than someone with 2000+ litres.

If I can control the production parameters, I can grow fish....and vegetables......faster. In fact, I can grow the same amount of fish in a small tank as someone else can in a larger tank just because I can achieve greater control of the parameters.

I also accept that I have to apply a higher standard of management....but that's fine. Given that we've also bred poultry and quail, we're used to that.

I test my fish tanks every couple of 3 or 4 days and I see my fish and plants at least twice every day. My partner will stick her nose into the shed another two to three times each day......just to make sure that everything is still flowing and bubbling.

On weekends, I'll probably spend most of my day in the shed....and while I'm making things, I'll be monitoring my systems......and learning.

amen, most of us would like to do that...

Generally, small tanks have been the blue barrels and the like with IBC's falling in somewhere inbetween - but I get your point


The temptation to do it more often is powerful!

Gary,
That is an idea I will use and had not thought of. If my auto feeder drops into a containment ring running a few inches underwater and I have a catch tray on the bottom about twice the dimensions of the containment unit at the top, then the top feeding fish and bottom feeding fish have a place to feed and the rest of the tank should stay cleaner.

BRAVO Gary! Just keep those ideas coming!

I'm not sure that this will prove correct Gary - but only time will tell. I am hoping to use a 2500 litre tanks and use the volume of water to help keep parmeters stable. One thing is for sure - having a smaller tank (and stocking rate) means less grow-bed space needed which therefore reduces the difficult in getting up and going. A mistake I have made is taking too long to get this side of things under control. Your fish definitelly look ike they have gone great guns since I saw them in January (can see how big they are in those bucket shots). Mine have stayed pretty much the same size as I have been feeding them bugger all while I organise new tank accomodation (getting them out of the small pond and into a 1000 litre tank) and aditional grow-bed space.

I can't wait to see what sort of growth I get out of them when I can start feeding them as much as they would like to eat :-)

Doug - let us know how that goes. Will be interesting to see if the bottom feeder come to feed at the bottom of the bucket.

I have the other extreme. Of course I can hold the water level and therefore volume down, but at 3' deep and the water continuously in the grow beds, I will have about 13,000 litres. I do worry about nutrient concentration. When I start with 400: 50-75mm fish and all new plants, I expect to need to augment nutrients to the plants. I saw a topic on augmenting plant feeding. I am going to read thru that tomorrow night.

This volume of cold well water needs to warm up and cycle before I get fish. Big tanks do have their problems! I just finished my grow bed construction (except putting the liner in). I will post on my system topic when I can. Perhaps with that much water, I do not have to worry about putting all the fish in at once?

There is no arguing with Gary's success with 1000 litre tanks!

Hi VB,



I have to be a bit more disciplined around feeding than I have in the past. On weekends, when I'm around plenty, the fish get more food than usual and that's when I start to experience high ammonia and nitrite levels......and dirty water.

On the matter of tank size.....

- the biggest issue when rearing Jade Perch (and other warm water species) is to keep the temperature at around the mid 20's. If you can achieve that, then it doesn't matter if you're using a 1,000 litre tank or a 10,000 litre tank.

- the biggest challenge with small tanks is to keep DO levels up and to keep ammonia and nitrite levels under control. I pump in plenty of air and carefully (most days) balance the amount of food that I give the fish against the amount of water that I use to keep my growing systems going.

.....and, so far, we're doing OK on all counts. I calculate that we'll probably be able to start harvesting fish with eight weeks.

For me, having a larger body of water, means having more tanks. My goal is to run different ages and species (in different tanks) for a given total volume of water.

For example, if we ended up with a total fish tank volume of, say, 4,000 litres, I'd be using at least four tanks and running at least two age groups for at least two different species.....for continuous production of fish and vegetables.

In my mind, small tanks (for backyard production) is also about risk management. If I lose oxygen in one tank (and my fish), that's a setback......but if I lose all of my fish in a larger tank, that's a tragedy.

You're certainly right about the quicker start up associated with small tanks. In fact, all you need to get going with a small set up, is a tank, some fish and a good bio-filter. You can then add coco-peat (or other media) tubs, trays and satellite pots as you can afford them and as nitrate levels gradually increase.

I calculate that I can put a small system......capable of growing in excess of an average yield of 1kg of fish per week......using off-the-shelf components......for less than $500.

Overnight, I completed the cleaning of my BSF larvae and, this morning, I put the last of them into the freezer.

For the past week, I've been feeding the larvae out to my fish. I put my original haul into small containers with some bran but I discovered that there was extra work in packaging them up. Over a period of days in the plastic containers they began to develop a strong ammonia smell and they continued to shed their skins as they progressed through the various stages of becoming flies.

I've been feeding frozen larvae for the past couple of days. The fish eat them with relish and I avoid all of the mess caused by the bran and skin shedding......and they now have no ammonia odour. They don't need to be thawed before feeding......the fish eat them just as they come out of the freezer.

My next challenge is to build a larger composting unit designed especially for Soldier Flies......complete with harvesting ramps and collection bottles.

Remember that heat loss is mostly proportional to water surface area. A larger tank that is deeper should be able to regulate temp better than the same volume flat.

Is there a formula for working out oxygen exchange on the surface? How much surface area do you need to get a complete passive oxygen exchange for each fish?

It seems to me that the cooling due to evaporation could be controlled by having a large tank with most of the surface covered - this would result in rapid water saturation with more opportunity for oxygen/CO2 exchange. Luckily this is what my tank uses, but it only just occurred to me that this is in fact an advantage.

Hi njh,



No argument with that, at all. What I'm referring to is the capacity of a smaller tank to be raised to, and maintained at, the optimum temperature (which in most places will require heat input of some sort) at lower cost than a larger tank.

Small tanks can be covered, too. I use small air pumps to ensure adequate DO.....they cost cents per week to run.

Small tanks (around the 1,000 litre mark) offer a raft of additonal benefits over large tanks........including the use of smaller pumps (cheaper to run).....ability to relocate (for renters).....cheaper to buy.....easier and cheaper to transport and to establish......easier to prevent unwanted access by children and animals......less obtrusive (for a backyard).....greater ability to control and treat disease.......and the capacity to run different ages and species (for continuous production).

Small square or rectangular tanks offer the added benefit of more effective utilisation of space.....easier to cover.....easier vertical integration of other systems (stacking for even greater space efficiency).

As I've stated previously, the only downside is the need for closer management since everything happens.....for better or for worse......faster.

Gary