Backyard Aquaponics
A place to discuss aquaponics

Hi Forum crew

Im working at Perth City Farm. We are an urban agriculture and food project in East Perth in WA. We have rebuilt an old BYAP aquaponics system that was unused here and have added a small aquaponics system donated by Suburban Farmer

System 1-BYAP (though modified)
2 growbeds 1800mm diameter by 380 depth
1 fish tank - 1800x800
1 sump tank
around 30 Silver Perch @ 150mm

System 2
1 growbed 1800x380mm
1 grow bed 1200x300mm
fish tank 1800x600
around 5 silver perch @ 250mm

we are having issues, after around 2 months these are the tests

system 1
pH-8.2 !!
Ammonia - 0
Nitrate - 0
Nitrite - 0

system 2
pH-8.4 !!
Ammonia - 0
Nitrate - 0
Nitrite - 0

tap water is pH 8.4

all plants dont look happy and we are getting quite a bit of algae growth. Will be testing our rainwater/bore water tank to see what pH is tomorrow. IVe had this issue before with alkaline tap water and its a real hassle to ever get neutral water. will upload pictures soon.

Im looking for some advice on dealing with alkaline tap water and re stocking densities for fish. what should i be aiming for?

thanks

Cover the fish tanks to block out the sun. This will kill off the algae that will be using nutrients that your plants need.
Then get some chelated iron (yates), and add a teaspoon to each system, as the high PH will be blocking out iron and maybe some other nutrients. The chelated iron is able to be absorbed by the plants at high ph.
Also add a dollop of seasol every week or so
Welcome

Here is a link to the system as it was back then and a bit of the history!
viewtopic.php?f=34&t=2438&hilit=city+farm

Clayton are you able to post up some pics so that we can see what the configuration is like now?
What are you feeding the fish and how much?
Mantis is right about blocking sunlight from the fish tank to kill off the algae. Run the pumps full time, this should also help. Perhaps you can add some yabbies as they are also good algae eaters and keep the bottom of the tank clean. Is there anything on the bottom of the tank, like leaves breaking down or places that detritus can collect. Hopefully it will be clear, you can check by running a small fish net across the bottom, sometimes children throw things in The more information we have the easier it is to help.

hi guys thanks for the replies and the trip down memory lane!

Faye, you might remember that i got the grant to fund this aquaponics system when i was last at city farm. I soon left to work elsewhere. The aquaponics system didnt really ever get back up and running. Now that im back, we are putting in effort to at least have a decent working aquaponics system that the public can view. not quite there yet

i will post some pics and info re fish today.

funnily enough, I had alkaline pH issues that were very similar in my last home (experimental) aquaponics system i built in 2008. It was built in a house that got sold so dont have it anymore.
viewtopic.php?f=18&t=4608

Ph always seems to take ages to come down, mine did. You may need to wait a couple more months but just keep adding the chelated iron and seasol.
As far as stocking with fish, this is what I have learned.
If you are stocking fish for food production have fish all approx same size. I feel this is not only for competition for food but also the edible fish are more likely to harras each other if size disparity is to great.
As for density of fish you should be able to find something on the forum search.
I have recently swapped to all koi and goldfish. I really think this has been a good change as they are very hardy, the big ones don't harras the little ones, they are pretty cheap and they look great. I still want to do edible fish but will develop a stand alone Ibc system for seasonal fish.
Maybe you could have one system for koi and goldfish and another for eating fish.

As a display centre, I think skipd might have a good suggestion. One system for fish you eat, one system for fish you don't eat. Some pple just cannot warm up to the idea of killing their "pet" (anything they keep alive for 2-3 weeks is a pet).

Great to hear you're resurrcting the system out there Clay...

some photos. info coming later today.

all systems are flood and drain with stand pipes as per BYAP original system. system 1 is on 15mins every hour and every 30mins at night. i think system 2 is on every 30mins. will check.

we are feeding fish some high protein feed bought of mike @ suburban farmer. less than a handful per day for both tanks.

no shade currently.

i like the idea of koi in one. i had that at my house but i was told that they dont excrete as much as silver perch etc. meaning less of an active system for nutrients for plants.

for pH, I used sodium bisulphate last time but it was a constant addition because of water top ups with alkaline water. any other suggestions?

really need this system to be looking good because its right at the entrance. everyone that comes to city farm or the cafe sees this. i want it to be a representative example to inspire people.

What were you trying to acheive Clay... and who told you to use the Sodium BiSulphate...???

re sodium bisulphate...cant remember...it was about 3 years ago but i was trying to get it to neutral and it worked, check out my posts on the home system. link is in previous post on this thread.

not sure how we will tackle the pH issue here at city farm. doing some more tests now. just checking to make sure the tests are accurate. distilled water is showing at 7.8

pH 7.8 isn't that bad for a system that's recycling... the pH will drop over time with nitrification...

If you want to give it a helping hand... treat your top up water with HCl acid...

pH 7.8 is the distilled water that we used as a test to make sure that the water tests were accurate.

pH of tank water is 8.2 - 8.4

our bore water/rainwater is measuring pH 7.8 with nitrate at 40ppm

Rainwater is lower Ph, or at least mine is( in bucket from rain).
As it has been operating before maybe it might drop a little sooner.
IMHO leave and not worry, it'll drop.
In regards to the koi I was under the impression they were quite a messy fish, but maybe not a messy as SP.
There are lots of koi farms around Perth, woodvale, nangara, swan valley are all good.
It looks like you have inherited are great couple of systems there,
The lack of shade may determine your planting choice.
Shade options, well you certainly have blank canvas to work with