Backyard Aquaponics
A place to discuss aquaponics

I have no fishies in my duckweed pond atm. duckweed in my tanks cannot grow fast enough.
However ppl, this is not surprising!
Simple conservation of matter makes sufficient production of duckweed unlikely.

every year we put in X fish weighing a few grams. Every year we take out X fish weighing 800g. We also take out a heap of veggies.

In order for the system to work, this energy, this foodstock needs to be returned.
We do this in the form of pellets and other added foodstuffs.

The only additional input we have is sunlight. That's a heap of sunlight to replace fish that have changed mass by 40,000% Whilst I'm sure theoretically it can be achieved, perhaps even practically, the surface area one would need is phenomenal.

So unless there's another way to feed the duckweed (a separate humonia pond) it'll never grow enough to keep your fish happy.

Hop in the wayback machine to 2006:

viewtopic.php?p=3969#p3969

Gee wiz Mister! That wayback machine is disorientating!
so... have you built it yet?

Nope, not sure what to use for the clear trays, although my fish would appreciate the nutrient removal these days.

I guess it really depends on how much fish you're trying to grow, but I know for myself and my family, I wont need to grow that many fish.
I have plenty of space (10 acres), so I could easily grow enough duckweed.

I'm thinking sustainable pasture rotation with small blocks in which I rotate first sheep in, then cows (they eat differently, so it helps the grass), then finally about 3 days after the cows rotate out I move chickens in to scratch all the dung and eat the maggots that flies spawn from. Then I take the manure, compost it and add it to my duckweed ponds. Duckweed ponds to fish to plants to my belly.

Hey kogane, if you have the land, use it :-)
I'd also have a look at certain grains and other crops to supplement their diet, don't ask me what, I haven't the land to make the investigation worth while.

I've been trying a bit of salvinia with the duckweed. Grows just as fast but has more mass. Threw some in the pool and the silvers ate it. Was looking at it more for mulch in the dirt garden.

I was thinking along the lines of adding a duckweed trough to the pee ponics system. Since with pee ponics you don't have to worry too much about the solids filtration capacity of the gravel, you only need enough gravel to convert however much humonia you are adding. Of course, the duckweed troughs could handle a fairly high amount of the ammonia before conversion. Still looks like potassium and trace elements would probably need to be added for such an upgrade to the pee ponics system.

Does anyone know the numbers off the top of their head (I don't have time to read through the other threads or articles at the moment to find the info) what temps does duckweed like best in it's air and water. And also what % of shade have people found to be most useful for growing duckweed?

I have it growing prolifically under metal haelide lights in my indoor FT as well as in my outdoor pond, under 4-6 hours sun. It seems to love light.
Heat from the metal haelide doesn't phase it, but it also grows strong in a melbourne winter.
Water temps indoors are up to 28, outdoors down to 10

it truly fits the description of weed. it is impossible to get rid of without doing a 100% water change or introducing a herbicide.

I've never considered conditions before, because it simply grows whereever you put it.

Ive got it growing without lights.......is under a few pieces of shade cloth and no water changes and theres heaps of it

I add a little o2 to the duckweed drums. Seems to make them grow better. Plus it slowly changes the water via airlift so I don't have to top them up.

Yeah lights are for effect... I was trying to say it would grow in almost any conditions...

Dont know about duckweed but heres my ozilla

ozilla or godzilla? ......your just showing off now milne arent u