Backyard Aquaponics
A place to discuss aquaponics

I think i may have found the problem the duckweed growing in the fish water
got to 1 in thick and when its that thick if you stir it up it realy stinks i think the rain stired it up the duck weed tank stinks like hell havent been down the yard for a couple of days just noticed tonight will leave till tomorrow for the experts to have a look comments would be appreciated

Agg drain already in impossable to get runoff .The water that came from the glass house got in an open end pipe

F&F have I read you right? You are now thinking that the duckweed tank got rank enough to kill off the fish?

Hi F&F,



Mate, from what you've described your duckweed tank is anaerobic.....that is completely without oxygen.

Could you describe the relationship between the duckweed tank and the fish tank? Are they hooked together somehow? Describe the water flow.

If your duckweed tank is hooked up to your fish tank, the chances are that the oxygen levels in your tank have been much less than they need to be to sustain your fish.

In that case, your fish weren't poisoned.....they died due to lack of oxygen.

Duckweed needs to be managed. Here's some information about plant density that I posted in a thread called "Optimum Conditions for Duckweed."



The capacity of duckweed to do what it has in your system is the reason why duckweed is regarded as a nuisance plant in many parts of the world. In the presence of nutrients, it will continue to grow until it turns the watercourse into an anaerobic, stinking mess.

I'll be able to tell you more once I know how water moves through your system.

Gary

Gary heres a rundown i have 2 ibs with 3 air stones the water goes threw the grow beds flood and drain there is no smell there the return goes via a 200 litre sump with an airstone a small pump runs the nft that return via the duckweed [ thats were you pick up the smell ] then back to the sump and the first tank all the water thats returning from the grow beds [1000 litres goes via the sump so that will be replenished]

F&F,

I'm still not sure from reading your post whether your duckweed water goes into your main tank and, if so, how much.....so I can't say whether the lack of oxygen was the cause of your fish deaths. I'd be surprised given the flood and drain action of your grow beds.

In any case, you need to clean up your duckweed tank so I'll try to help you out with that.

Harvest the all of the duckweed except for a small amount to kick off your duckweed growing again.......perhaps just enough for a single layer of duckweed across your tank. Pump the water out of your duckweed tank and replace with clean water.

Don't waste the duckweed.....this is a good time to do a duckweed trial.

Wash the harvested duckweed to remove the smell......then gather it up in a kitchen sieve and tap it to remove any free water. Spread the weed out on some newspaper....several sheets thick. Turn it several times during the first day or two. Keep it out of the wind or it will blow away.

When completely dried (three or four days at best), bag it up and put it in the freezer. If your wife recoils in horror at this suggestion, put the thoroughly dried duckweed into paper bags and store in a cool dark place. Your fish will enjoy that when your fresh stocks run out in Winter.

Obviously, your system grows duckweed well enough so you might want to make this a regular thing.

The goal is to keep enough duckweed in the tank that it suppressed algae but not so much that it mulches itself into the stinking mess that you're experiencing. Harvesting the duckweed at not greater than weekly intervals will help to avoid your current problem.

Have a good day today with the Meet.

Gary

2 questians i have salvaged some plants from the nft i have them floating in 800 litres in an ibc [how nuch seasol do i need th keep then alive] 2nd one how much bleach per 100 litre to sterelise the beds and will it kill the tomato or do the beds just need a good flush

Hi F&F,

Just put a couple of capfuls of Seasol in for the duckweed. They can grow on traces of nutrients......you can always put a bit more in later if they need it.

The chlorine bleach will only impact your system if there was a biological explanation for your fish deaths.......like a bacterial infection or a virus.

From everything I've read so far, it appears that poison from your greenhouse was the most likely reason. In that case, you just need to fill them up and run the system......flushing the growbeds.....and then dump the water. When you've done this at least three times, try some cheap fish in the water again. If they survive a week, you've probably got rid of the poison. If not, you'll need to keep flushing until your system will sustain life.

Gary

Put pond safe from aquamaster in today Ph now 7.6 amonia.25 what next

flush your beds a few times with tap water (flood the hell outta them then leave the hose in there while draining) then connet the ibc back up again.

the trace ammonia will help in re-establishing your bacteria.

GD was spot on about the bleach

what filter do you have in your aquarium? can you steal some gunk outta it? If not i can leave you a bag full on my front step. let me know. insta bacteria

i assume pond master was the de-chlorinating agent? If so then there was .25 PPM chloramine residual after what, a week and a half in the ibc, no sun, but bubbles.

yep pond master is a declorinater fron coberg fish place .25 is anonia there was no anonia before i put the dechlorinator in thanks i have some filter gunk

Looks like the tide has turned the first ibc has been cleaned sterelised filled
degassed the duckweed tank also and i have had gold fish living for 2 days now yippee

Good to hear

more power to you F&F

Went to Lyndsay and Glynis kangaroo ground fish farm today just a small set up probley $ 1000000.00 set up about 15 large tanks number of small tanks 4 bio filters and you want to see his aqua setup floating raft style 2500 plants being fed buy two fish tanks of 9000 litre each 600 fish in each he has fish in a neutrient solution supplying hydro beds[to keep the mossies down] learnt how to cut holes in styrine [hot bit of pipe ] man next time i go i will spend more time for shore . Any body into fish in victoria go there you wont be dissapointed