Backyard Aquaponics
A place to discuss aquaponics

hi all

i have recently started up a system with a 1000lt tank and 100 rainbow trout.

ive been running now for a few weeks and the plants are growing well (still small) in a 200lt growbed

i tried to cycle this system with 20 goldfish but it seemed like the fish were to small and it was taking too long because i couldnt even detect ammonia at all after 4 weeks.

so i just bit the bullet and bought my 100 stock fish

at temperature of 17 - 19 degrees celcius, ph 6.4 - 7.2

im getting ammonia readings between 4ppm - 8ppm (or higher)

Nitrite 5ppm maybe higher

Nitrate 5ppm

im using the Famous API Matster test kit as it seems most people are familier with


ive had a small system crash on me before around this same time so ive been doing 25% - 50% water changes with declorinated water

i have worms in the growbed and an improvised swirl seperatator to remove solids

theres plenty of airation and no sunlight hits the water

there is a a vague smell to the water but nothing to alarming

the water was clear untill i added the trout then it darkened and hasn't cleared

the fish are ravenously hungry i have to restrain myself from overfeeding as they always eat everything quickly!


i want to know whats going on with the ammonia and nitrite levels as i cant keep changing water endlessly ... i fed them less today and im not going to feed them tommorow.

are these levels going to settle down?

should i tough it out untill the ammonia and nitrite levels settle down?

any advice is welcome

Hi Carl and welcome to the forum

To be blunt with you - you are extremely overstocked and I will be surprised if any of your fish survive. The ammonia load you have introduced to a virgin system is too much, your nitrite and ammonia levels are heavily toxic right now.

Why did you think you could have 100 trout with only 200L of filtration? Thats madness! You need around 1000L of filtration for that many fish and definately a lot bigger fish tank.

Maybe you can find someone in your area with another system you can share your 100 fish with, or sell some??

I dont think they will last long enough to share. Sorry man but 100 trout in that system is madness.
I have a system with 1000L tank and 1500L of growbeds that has been running for many months and am going to get 30 trout tomorrow and will monitor them for a while without feeding

possibly the ol' 1 fish per 10L me thinks....

Actually... for 100 fish... you need closer to 2000L of filtration capacity...

If you're already doing water changes, and your ammonia levels are still above 2.... then Frankly, I'd be surprised if your fish survive...

Do NOT feed... AT ALL....

Salt to 1ppt to mitigate against nitrite poisoning.. if it's not already too late...

Do whatever water changes are necessary to bring your ammonia down below 2... below 1 if your water changes push your pH towards 7, or higher...

And either add another four grow beds immediately.... like this weekend....

Or get rid of 80% of the fish.....

my terrible maths.....correction - 2000L filtration as Rupe mentioned

been a long day

possibly! ( i dont think the person who put that number out there would have sugested that type of stocking with that much(little) growing area & a New system to boot!)

but it's all about the filtration! and filtration from a properly run in Bio Filter i.e 12 month old grow bed would be good!

And as rupert has said! up to 2000 liter's i would go higher to give you some buffer but hey thats Me!

carl01 unfortunatly there isn't much you can do apart from getting the fish in to more tanks or changing water as often as possible!

thats all right you where thinking 1:1, rupert was thinking 2:1

Huh? I think the person that put that number out there did exactly that.....put that number out there! Regardless of filtration capacity.


thats all right you where thinking 1:1, rupert was thinking 2:1 - no sadly that was my maths on 25 fish per 500L

Yeh ok then

I've got a deep flow hydroponics system that's about 12 months old with 20-30 well established plants in it could I use those growbeds to help with filtration?



Also where could I find guides as to correct chemical levels I've got an ammonia chart but can't find anything much for nitite & nitrate!

Also where can I get the numbers to help calculate fish-growbed

Any lateral thinkers out there with solutions to my problem please reply

I've looked back to see why I chose the number i did and even though I have 100 fish ur only talking 10 - 15 kgs of fish for the system at this stage the reference I worked off says between 10 - 30 kgs is fine

Any thoughts?

Hi Carl

You will need to stop feeding the fish, for now. They will be OK without food for many days.

You need to keep changing the water, with dechlorinated tap or rain water. 20% to 25% min everyday, until things settle.

If you have an established aquarium/pond, place the fish in that.

Please note that it is never about fish numbers, but how much waste/ammonia they produce (size of fish). You could easily have a few thousand trout, in 1000 l, if they are newly hatched.

What size are your fish? Approx what overall weight do you think you have.

You need to get as much beneficial bacteria in your system, as quickly as you can. These bacteria are surface dwelling and are present in all established healthy water systems. What you can do is get that bacteria from a system, and shift it to yours ASAP.

Go to a farm dam, pondage, river/creek, reservoir and get a heap of material. Material such as aquatic plants, detritus, sand/rocks, roting tree branches etc and place it in your system. You can place some of it in a bucket, for later easy removal. It may make your water murky for a while, but that's OK, as the particles will have the needed bacteria on it.

Do it now!

ok

so todday i did an 80% water change followed by a 90% water change afterwards, i also went down to the local river and grabed a branch out of the water and threw that in the tank.

i added alot of bottled bacteria as well.

right now ive got

0.25 ammonia

0.5 nitite

0 - 5 nitrate


i fed the fish in between water changes because they hadent eaten for two days

most of my fish are small about 2 inches long

i did however get 10 bigger ones as well so today i took out the two biggest ones and ate them, they were delicious!

so now ive got 90 2 inch (and smaller) trout and 8 that range from 3 inches to near plate size (300 grams)

i added a small 90mm pvc growbed i had from a previous setup that i had lying around to help with filtration ...

however its not very big


hopefully this will help


Thanks for the advice everyone

2" with plate size? the bigger ones will thin them out a bit..