DIY Aquaponics - Using Your Aquaponics System

So lets assume at this point you have assembled your DIY aquaponics system or you have purchased one of the many excellent kits that are available these days and it is installed and ready to use. Lets have a look at the day to day running of your aqauaponics set up starting from a brand new system.

Getting Your New System Running

Its going to sound really obvious but lets start by filling your fish tank up with water and your growbed with gravel. If the water you are using is chlorinated the chlorine must be removed. If your water is chlorinated by chlorine gas then simply let it sit for two or three days and the gas will disipate. If the chlorine is added as chloromine then you will have to use a water aging solution making sure it is suitable for fish that are for human consumption. There are water test kits available from aquaponics and aquarium suppliers that will allow you to confirm that chlorine is not present. Turn your pump on and let your aquaponics system run for at least a few hours making sure it works as it should and that there are no leaks. If its an autosyphon system it can be useful to measure the length of time that it takes to flood and drain the system.

Once you are satisfied that the system is ready to go it must be cycled to establish colonies of beneficial bacteria in the growbed as described in the bacteria page of this site. To briefly summarise this a source of ammonia is added to the tank and the system is allowed to flood and drain as it would if it contained fish and plants. This will allow a colony of bacteria to establish itself in the grow bed. As it takes about three weeks in favourable conditions for the tank to cycle and the bacteria to become established its at this point that you could take a gamble and plant some seedlings in punnets to be later transplanted into the growbed. While the tank is being cycled use an aquarium water test kit that allows you to measure the levels of ammonia, nitrites and nitrate in the water. Perform these tests every day and write down the results, once you have found levels of ammonia and nitrite of 5ppm or higher and that then have dropped down to zero your tank has cycled. You should have measurable levels of nitrate if this is the case.

At this point you can safely contact your local fish hatchery and order your fish fingerlings. Regardless of whether you pick them up in person or they are freighted to you your fish usually will arrive in a plastic bag just like buying a goldfish from your pet store. Place the unopened plastic bag into your fish tank and allow it to float there for a couple of hours. This will allow the water in the bag to slowly change temperature to match the water in your fish tank and reduce the shock to the fish when they are released. After this two hour period open the plastic bag and allow some of the water from your tank to mix with the water in the bag and then allow a few minutes for the fish to grow accustomed to it. Release your fish into the tank gently and make sure there are none left in the bag before you discard it. Let them settle in a bit before feeding them.

When you first introduce your fish into the system they are usually small and dont create a lot of fish poop. Some aquaponics enthusiasts prefer to wait a week or two for the fish to grow a little and bacteria to become more established before adding plants to the growbed. This is not a dangerous practice at all as long as you continue to closely monitor your ammonia, nitrite and nitrate levels, which you should do at this critical time anyway. These levels should be tested every day for at least six weeks after adding the fish and then tested weekly from there. If your like me and your vegetables were seedlings when planted out it makes little difference.

Running your Aquaponics System

The day to day operation of your aquaponics system is remarkably easy and low maintainance. Generally speaking I have to spend perhaps twenty minutes a day with my system at the very most. Of course nothing stops you from just standing there and enjoying the sight of your fish and watching your vegetables grow, tending my system is in fact the most peacefull part of my day and I enjoy it immensely.

The water level in your fish tank must be maintained at a reasonable level, for example my system holds 500 litres filled to the brim but I usually aim to keep the water level at around the 450 litre mark. I top it up at the 400 litre level with five buckets of dechlorinated water. As aquaponics is a closed system the only water losses you will experience will be caused by evaporation or the transpiration of your plants. A lot of the fish poop will end up in your growbed but some will remain on the bottom of your fish tank and should be removed. I syphon it out using a length of ordinary garden hose which makes a very effective underwater vacuum cleaner, syphon the water and poop into a bucket so if you accidentally suck up a fish fingerling you will be able to return it to the tank rather than letting it suffocate on the lawn.

How often you feed your fish is a personal choice to a degree governed by your lifestyle and available time. They should be fed at least once a day of course but I prefer to feed them once in the morning and once at night, breaking that one larger meal into two smaller ones. Remember that if you overfeed your fish then uneaten food will contribute to poor water quality. Its a good idea to skip feeding them for a day now and then, particularly if you can see uneaten food in the tank.

Your growbed, particularly as the fish grow bigger and create more poop, should be well filled with plants. You can ignore recommended plant spacings to a degree as aquaponics tends to ensure that the plants root system receives a steady supply of nutrients. If you are propagating your own seedlings make sure you have a constant supply to replace the plants that you harvest, for example bok choi matures in 8-10 weeks and a bok choi seedling will be ready to transplant at 4-5 weeks. So as you plant out your growbed with your current batch of bok choi seedlings its a good time to start some more so that they will be ready to replace the current seedlings when they are harvested. When you harvest your crops do your utmost to return the gravel accumulated around the roots back into the growbed and replenish it if necessary to keep the depth of the medium at the original height.

Continue to monitor the ammonia, nitrite and nitrate levels in your fish tank on a weekly basis. If levels of one of these are dangerously high then drain on third of the water from your tank and replace it with fresh unchlorinated water and commence daily testing until the problem is resolved. Observe the state of your plants as well and make sure they are green and healthy. For the first couple of months as your system becomes established they will not grow as vigorously as they would in a well established grow bed. If your fish are small they may simply not poop enough to keep a full growbed nourished and you might consider only planting out half of the growbed to start off with.

Pest Control, Chemicals and Your Fish

Most chemical pesticides will kill your fish! Its sad but true that when you take the step down the aquaponics path there are several caveats, one of them being the effect of many pest control sprays and dusts on your fish. If you are currently a more traditional gardener go down to the garden shed and look at your tomato dusts, derris and pyrethrum bottles. Chances are that the labels will contain many stern warnings about how deadly they are to fish. Using them is simply not an option.

But thats ok because we want an organic garden anyway, right? One option is to build a greenhouse around your system so you can control what insects come in and out a little better. I manage pest control in my open air aquaponics system quite effectively without using chemical pesticides using three seperate but combined approaches. Biological control by encouraging the presence of natural predators such as lady beetles, praying mantis and spiders is an effective step. Manual removal of pests is also effective, pick the caterpillars etc off your plants and toss them into an icecream container, when you have gotten all that you can find empty these unwanted guests into your fish tank, your fish will love them and it will save you some feed too. For really bad insect infestations do all of the above and finish off with a garlic spray made by mincing garlic and soaking it in water. Strain the garlic off and apply the garlic spray to the plant leaves by a pressure sprayer. It really gets the bugs on the run. Repeat this regime for a few days and you will soon notice a drop in pest populations.