Yokohama International School Aquaponics System

Here is your new system!

1.  Fish Tank (220 litre plastic tank)

2.  Growbed (180 litre plastic tank)

3.  Growing media (lava rock)

4. Pipe from pump

5.  Nutrient delivery pipes

6.  Media Guard

7.  Overflow pipe

8.  Growbed stand-pipe

9.  Pump



Weeks 1-6











Building Bacteria! ("cycling your system)


Our first step is to build our bacteria colony in the growbeds and the fish tank.  The bacteria that we want is attracted to ammonia... and so we need to add ammonia to the system.  Building a strong bacterial colony in the system will make it very resilient and productive.. and the good news, is that these colonies usually get stronger and stronger over time.  The bacteria converts the toxic ammonia and fish waste to something that the plants can eat.  The plants then clean that water for this fish and everyone is happy!



The good news is that fish naturally give off ammonia, and so we can start our system by adding just a couple of fish to the tank.  They, and their food, will give off small amounts of ammonia which will start to attract the bacteria we want.



You can add seedlings to the system at any time during the first 1-6 weeks.  The seedlings mostly require water and sunlight to grow in this stage, and so they should be absolutely fine.  There will not be many nutrients in the water at this time, so if the plants are struggling a little bit, then you can add a natural seaweed liquid (Maxicrop or Seasol for example) just to give the plants a little boost.  Any additions MUST be 100% natural products though.



During this stage you can run the pump 24 hours a day if there are no plants in the system - but when you add plants you should then change the settings so that pump is ON for 15 minutes and then OFF for 15 minutes.  This cycle is repeated constantly.



We need to make sure that the bacteria are developing in the system, so we need to start checking the water to find out a little of what is going on.


•  Check the pH level in the water 2 or 2 times a week.

•  We need a pH of between 6.8 and 7.2 if possible as this is the optimal balance for the fish, the plants and the bacteria.


•  Measure the ammonia ( NH3) level in the water 2 or 3 times a week.  Please use the test kit provided and record results.


•  Once we have ammonia then we need to check to see if nitrosomonas bacteria are there by measuring nitrites.

•  Measure the nitrite (NO2) level in the water 2 or 3 times per week.  Please use the kit provided and record results.


• Finally, Once we have seen nitrites then we need to see if nitrospira bacteria are there by measuring nitrates.

•  Measure the nitrite (NO3) level in the water 2 or 3 times per week.  Please use the kit provided and record results.


japan aquaponics nitrogen cycle

This chart will give you an idea of what might happen in your system.  As the ammonia builds it attracts Nitrosomonas bacteria which convert it to Nitrite.  At that point the ammonia in the system should decrease to almost nothing.  If you have high ammonia but no nitrites showing, then please stop feeding the fish for a few days.


Once the Nitrites appear then this will attract Nitrospira bacteria, and they will start converting the nitrites to nitrates.  At this point you should end up with a system that has almost no ammonia and nitrites in it - but lots of nitrates.  You have done it!




It is good to get to know your system - watch the fish every day to see how they are getting on, and check the system to see if there are any leaks, or if any pipes have come undone perhaps.


Once a week it may be a good idea to give the inside of the tank a bit of a clean - just brush it down with a soft-haired sweeping brush - be careful and don't fall in!  Check the pump to make sure that nothing is tangled up in the intake, and that it is working smoothly.


If you look inside the Media Guard you have to be very careful when taking the yellow cap off - remember... you must NEVER remove the Media Guard because you do not want the lava rock to get inside it!


Look at your plants and seedlings once they are in the system - are they looking healthy?  Do they have any spots?  Do they look nice and green, or is there some yellowing on them?  Are there any insects or bugs on the leaves?  Just do a regular check to make sure that everything is looking healthy.


Finally, look at the fish... do they look happy?   Swimming around?  Are they eating, or is their food still floating on top of the water?  If there is too much ammonia in the system then they may be feeling a bit sick... so stop feeding them for a couple of days and replace some of the water with fresh water.


Starting Seeds


You can use almost anything as a container to start seeds!  The best idea is to get creative and look around you to see what you can reuse, or recycle as a seed pot.  Common ideas are used toilet roles, egg shells, egg boxes, used tofu boxes, tissue balls, old yoghurt pots... just use your imagination!  It is a good idea to wash out any plastic or organic containers (like the egg shells) and then line them with a piece of kitchen towel to help retain moisture.  For best results cover the containers with a clear plastic bag, or a clear plastic lid, to raise the humidity higher and protect seedlings from rain or wind if they are outside.

japan aquaponics starting seeds
japan aquaponics starting seeds
japan aquaponics starting seeds
japan aquaponics starting seeds


Aquaponics does not use soil, and we really do not want to add any  to our system - and so the best things to use to start seeds is a small, inorganic material like:  Vermiculite  :  Perlite  :  Hydroton  :  Pea Gravel  :   lava rock  :  or simply wrap the seeds up in a small tissue bundle (but remove before you put into the aquaponics system)  All the growing media should be small in size - just a couple of millimetres if possible.

japan aquaponics starting seeds media
japan aquaponics starting seeds media perlite
japan aquaponics starting seeds media
japan aquaponics starting seeds media hydroton