Backyard Aquaponics
A place to discuss aquaponics

I wonder how much potassium a banana skin adds to a system. So many tests and not enough time..

The trace element content of aquaculutre feeds is very minimal... designed to provide essentially just for the needs of the fish themselves... (primarily calcium & phosphorus)

Yes, feeding twice as much feed... would result in the intake of twice as much of the trace elements... and twice as much output into the wastes... which would accumulate in the grow beds...

But analysis of fish wastes... shows the mineral content... other than phosphorus.... to be a pooftenth of a unit of one percent.... in total... let alone Potassium...

That's why Potassium is almost always required to be supplemented in AP...

thanks for clearing that up.

Seasol is potassium right because i read it wasnt N or P?


i will be getting some more fish anyway due to the lack of nitrates etc, i was feeding them 2-3 times a day currently.


Last question for now,

I was using clear pvc tubing (food grade) because i had to move the system so i liked the flexibility.

As can be expected a nice layer of thick slime grew inside (im assuming its not biofilm??) i was guessing because its in the light that its a form of algae, it actually looks like a thick sheet if you pull it out, like someone made some jelly when its set. Ive since removed some of the piping so thats its not going to return.

COuld this algae be using up any of the available DO?? and making the system a bit more anaerobic?

Seasol is "relatively" high in Potassium... (low nitrogen/phosphorus)... in terms of N:P:K....

Whereas "Powerfeed"... has a higher (relative) nitrogen component... N:P:K

Many soil gardeners combine the two....

In regard to algae in your clear tube... yes it will use some DO.... but not significant...

And don't clean off the "bio-film" jelly like coating... it will just grow back anyway... but it will also protect the tubing to a degree...

Otherwise the tubing... as it's not UV stabilised... will just eventually break/crack... (it will eventually anyway)....

no probs, thanks for the info.

Ill pay more attention to potassium levels now i know what to look out for.


The other thing i see is chelated iron, is this the same as potassium? maybe once a month or so needs a small additive?

Iron is something not formulated into aquaculture feed and will always be required as an addition to your system for plant uptake.

A safe measurement thrown around is a levelled spoonful per 1000L of FT per month. But, the only real way of knowing for sure how much and when to add is with an iron test kit. You dont want to exceed 4ppm.

thanks for all the info dudes.

Picked up a couple of show koi that are approx 15-20cm long.

I have also put some chelated iron in (~1gram).

I will add seasol and iron once monthly from now

I need to test nitrates now because with all the things ive changed and having no plants in there i think that might start spiking ><...time to dig up a plant from the garden and put it in there to be safe.

since i added teh extra 2 koi, and some powerfeed i realy dungoofed...

As i pulled out the plants that were in there when i moved it now my nitrate and nitrite is off teh chart ><


So i grabbed some plants from the garden, washed them off and put them in there to hopefully start sucking that stuff up...

ammonia and nitrite are down now....nitrates to the moon.


The joys of adding more fish whilst remembering you just pulled out all of your plants