Ugh, duckweed

DailyLunatic said:

This week I bought a kilo of duckweed for my two ponds.
Looked good and healthy, but arrived stinking to high heavens (so might have been dead from the outset. dunno.). Divided into two portions and tossed into the ponds within 30 minutes of arrival.
Next day, gone. Only a very few white bits are clinging to the banks. No fish in ponds yet, so I know nothing ate it.
I CANNOT keep duckweed alive.
Trying Azolla next.

-sterling

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Sgooosh said:

hello! is the water stagnant or slow flowing?
how much sunshine is there?
duckweed likes slow flowing water, but not completely stagnatn, and also part shade to full shade rather than sun
azolla tolerates much more sunlight, and it doesn't like flowing water.

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DailyLunatic said:

I wasn't sure on the duckweed, light wise. I read a lot of conflicting information. Duckweed was cheep, (less that $2 for the kilo) so I gave it a go first.

It died overnight, so I'm not thinking flow rate would not be enough to cause a die-off so quickly. In fact, I dispersed about 2:00 pm on day 1, and by 8:00 am next day it was gone. It's either the sun, or it was dead when I got it.

Ponds are stagnant, and receive full sun. -Thailand- full sun. Plans are in the works to drill a well, and have the pump on solar. That's currently on hold due to the fact that he can't get back there to drill until Dec, or Jan... When that happens there will be some slight turnover, even if it is just a recirculation pump.

I have Azolla on the way. I'll post again when I have some results...

If you can suggest an alternative to Duckweed, or Azolla, I'm all ears. Dual purpose here is to a) create a augmented food source for the chickens & Tilapia fish, and b) remove nitrates in the Tilapia pond eco system.

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Sgooosh said:

hmm, i think full sun might be the reason. it murders duckweed, is the duckweed white when it dies?
you can get a small container under shade and see how it does. since you want it for food, it's best to have a shallow container under a tree. they grow fast even in shade. put some pest snails in there with clean water and it will be a mini ecosystem that farms duckweed. pollen, fruit, and debris that falls from trees will be food for the ecosystem
was it green when you got it? and fresh?

you should do azolla, because it is much more heat tolerant. it grows lush in full desert sun, no moisture and 110 degree + weather and 90 degree+ water daily.

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sharkweek178 said:

So I have duckweed in my tank now. I'm a little embarrassed to say that I didn't even realize that's what it was at first. I know where it came from. My own fault, really. I bought a couple of assassin snails from a shop and the tank they were in at the store was lousy with duckweed. I was a little hesitant at first but I decided to go through with the purchase. There was even a couple of pieces in the little plastic cup with a lid they put the snails in. I carefully removed it. I put the assassins in a jar to quarantine them. But clearly not for long enough.
It's more annoying than anything. It's not like it's going to harm the fish (unless I let it overrun the tank) and there's actually some benefit to it. I'm not about to buy a goldfish or dump herbicides into my tank. The only thing to do is an aggressive removal routine every day or two. Maybe I can get rid of it, maybe not. At this point, my expectation is to manage it. And I'll use dedicated equipment for this tank to hopefully avoid spreading. I'll do the water change for this tank on a different day too.

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Blackghostknifekid said:

what fish are in your tank?
larger cyprinids like to eat it.

Scoop as much out as you can.

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sharkweek178 said:

The largest fish I have is a honey gourami. So the fish weren't going to fix it for me. I spent a few days taking out all the salvinia minima and Anarcharis and clearing out the duckweed. It was tedious. But it got the job done. Not completely. When I do water changes, I still find a few pieces of duckweed. I just take those out as I find them. The important thing is that it's not overwhelming the tank.

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Blackghostknifekid said:

You need to clean the net in hot water. Near boiling. After you clean it by hand.

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DailyLunatic said:

It disappeared. I can't testify to its color. When received, the first batch of Duckweed was approx. 1kg, a dark green color, and stank to high heavens. Took one half day for it to disappear, and two days for the stink to wash off my hands.

Cut to present. - Day before yesterday I received two more packages.
1 was a small baggie of Duckweed. Less than 10g dry weight, estimated. Floating in about a pint of water. Sweet clean smelling, but not a lot there.
The other package was a large plastic bag of Azolla. Damp, but no standing water. Estimated 1kg dry weight. Bag had a 1" dia. ring at the opening, and tied in place to hold open (I assume for air exchange). This bag too had a clean and grassy smell. They each cost about the same. Better bang for the buck (or in this case, baht) is the Azolla, and I will be leaving very positive review with the seller.

Both went into the ponds late on day 1.
Day 2 - I had to drive into town early and stay late. (New passport arrived and I had to report to Immigration. Just took forever...) I did not have an opportunity to look at the ponds.
Day 3 - I looked at the ponds and found few Duckweed, but admit it would be intermixed with the Azolla and hard to notice. But they were present. The Azolla had spread out, so it was difficult to estimate volume, but looked like about a 15%-20% reduction. Green color was slightly lighter, but not to a dangerous point, imo.

This is the first thing purposely put in the ponds that did not die on day 1. So, I'm happy with the results, so far.

pH of the ponds are 6.32, and 6.54 respectively. Both are discolored an opaque white, with a slight green tint, and have been for some time. There are plenty of tadpoles, water bugs, and frogs. They appear to be nibbling 'around' the Azolla, not eating the plant itself. I suspect small fresh water 'plankton' equivalent are attracted to the Azolla, and they are feeding on them.

If these survive for a few weeks I plan to add a few hundred Goong Ten, or Dancing Shrimp to the ponds. They sell them them everywhere, just mostly for eating. https://migrationology.com/thai-dancing-shrimp-serving-thailands-most-lively-dish/
Looking into these, just to get things started, and if they will work as the cleanup crew for the tilapia later. I expect they will just end up being a food source at that point. Sister-in-law grows giant prawns that I will eventually transition over to.

But I'm getting off topic. Sorry.

-sterling

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Sgooosh said:

I'm thinking something ate it or you got really bad dead duckweed.
I ship duckweed and it doesn't smell bad after 2 days.
any photos of the duckweed before?

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