Backyard Aquaponics
A place to discuss aquaponics

In our garden we have large pots growing lotus. The pots are filled with water and have lots of small fish (to stop mosquitoes breeding).

The lotuses generally grow well, however to encourage them to flower we and solid fertilizer balls every 2-4 weeks. I'm not sure what's in them, they are very hard a little smaller than golf balls and look like clay.

As they help the plants flower, I guess they contain phosphorous, so I was about adding them to grow beds. They don't seem to harm the fish.

Is anyone familiar with these fertilizer balls?

sounds interesting though, do you have the packet they where bought with?? or could you ask the supplier, I would be interested to know a bit more about them, especially if they are fish friendly

No one uses any fertilizer - except urea, and seaweed emulsion.

The only thing is are they food safe?

Fish feed/fish poo (at least fish that are being fed up for eating) usually has plenty of Nitrogen and Phosphorus. Most people find they only need to supplement Potassium, Iron, and pH buffering. Seasol or Maxicrop (original 0.1-0-1.0) seem to work well for potassium and trace elements.

During fishless cycling people will sometimes use urea balls as the nitrogen source but most people won't use that much if ever after fish have been added to the system.

These particular fertilizer balls I know nothing about, sounds like they are a slow release item. The biggest question is do they contain anything that would be bad to have build up in a food system. Since Aquaponics is a recirculating system you need to be very careful about adding anything that could build up undesirable things like heavy metals or other unknown chemicals.

You at least know that the mosquito eating fish are surviving in waters with these fertilizer balls but be aware that different types of fish will react to certain chemicals differently.

If you can find out more details about these things it would be interesting to know.

Thanks for the help. I've done a little research and found the balls do contain slow release fertilizer (as suggested). In fact they just seem to be small fertilizer pellets covered in clay.

I thought aquaponics was fine for nitrogen, but the potassium and phosphorous were low? Some of the plants in my system are looking a little yellow, however I'm now starting to think this is due to being too wet, so I'll switch to a timer based system.

Maxicrop and Seasol aren't available in Thailand and I'm having trouble finding alternatives (see the thread on chitosan fertilizer). I will probably start to make my own from worm castings, however I'm even having trouble finding the worms!

Can't you get seaweed or fish emulsion extracts anywhere Plachon... that's all Maxicrop and Seasol are....

Wonder if "fish sauce" would be any good... obviously would depend on what additives they add...

I haven't seen any seaweed based fertilizers, but will keep looking. Maybe they eat all the seaweed?

Regarding the fishsauce, hadn't thought of that. I think it's made from fish left to dissolve over time, something like that! Regarding the additives, let's hope note because there's plenty in the food. It's mainly salt though, so I'm not sure about the benefits.

I've seen farmers making their own organic fertilizers, which I think becomes a liquid. I'm trying to find out more. There's a big push for organic farming here, but ppl don't have much cash, so they use manures and do their own composting.

I have used fertilizer balls in my aquarium. Plants need micro nutrients, and macro nutrients to grow. A lot of these come from fish waste, but dosing them ups the amount available to the plants, making them grow faster and nicer. The balls i use do not contain phosphates nor nitrates, which is good when you are putting them into water with fish. The clay acts as a nutrient store, binding excess nutrients and releasing them as required. they did wonders to the plants in my aquarium.
the yellowish of your plants will be a lack of Iron.