Duckweed/Azolla Floating Rafts.

[DailyLunatic]

In another thread I've been discussing my woes trying to get Duckweed, and/or Azolla started in my Fish Ponds without success. The general consensus is that the sun is just too much for them here in Thailand.

My original intent was to have both Duckweed and Tilapia in my ponds. Duckweed floating in rafts above and the fish below. The rafts have a subsurface, boxed, netting to keep the fish out. This set-up allows for the harvest of Duckweed as feed for other animals (chickens for example) Three rafts in each pond would allow for rotation of weekly harvest.

As I was already planning to have the Duckweed in floating rafts, I'm wondering if the addition of a sunshade might be possible. Arched, tented, or boxed above it.

Downsides:
too much light blocked, no growth
sunshade acts like a sail and wind carries the raft away
difficulty harvesting as shade would need to be removed each harvest.

I've attached a few screen grabs from YouTube discussing this topic (without the sunscreen) in three different construction techniques. Not sure what is allowed re: vids.

Looking for suggestions on how to attach the sunscreen, and address each of the downsides mentioned.

My current preference is the 3" UV resistant PVC filled with empty water bottles in case of leak. That's also pretty much the most expensive, so adding too much more costs to it with a screen, is going to put that out of the running.

Looking forward to your input.

-sterling

 

[Magnum Man]

we have duckweed that grows naturally on our lakes in full sun, so I think if you get some from a source that is already exposed to full sun, you'll be fine without a shade... from our "growing fish thread" you may also have issues with the ponds being new, & in need of more nutrients for the duck weed to grow... which could remedy it's self as the fish get established... you may be trying to get everything going too quickly???

 

[DailyLunatic]

we have duckweed that grows naturally on our lakes in full sun, so I think if you get some from a source that is already exposed to full sun, you'll be fine without a shade... from our "growing fish thread" you may also have issues with the ponds being new, & in need of more nutrients for the duck weed to grow... which could remedy it's self as the fish get established... you may be trying to get everything going too quickly???

Ponds were dug mid April, so, three months? What would be the recommended wait time?

Also, not mentioned in this post, but I discovered the wife has been using the ponds as a midden, (dump for kitchen scraps) for about a month, now. I expect there should be plenty of nutrients. No 'green water' though. Just milky white.

-sterling

 

[GaryE]

Water hyacinth is common in your region, right?

 

[DailyLunatic]

Water hyacinth is common in your region, right?

I will look into it more.
It appears that it 'can' be used in animal feeds. My goats should be able to take it, as-is. However, I expect I would need to process in some way to feed to the chickens and fish.
I'll keep this one in mind if I can't get a solution to the floating rafts.

-sterling

 

[StevenF]

on a clear day in full sun light levels are up to 20,000 lumens . In my experience the primary reason why duckweed does not grow is lan of nutrients. In high alpine lakes were the water is mainly from snow and rain you often see no aquatic plans and little to now algae. But at lower elevations the water has picked up significant quantities of nutrients and Algae and plant can grow.

Do you have any fish in the ponds? Fish waste would provide nutrient for the duckweed.to grow.

 

[DailyLunatic]

on a clear day in full sun light levels are up to 20,000 lumens . In my experience the primary reason why duckweed does not grow is lan of nutrients. In high alpine lakes were the water is mainly from snow and rain you often see no aquatic plans and little to now algae. But at lower elevations the water has picked up significant quantities of nutrients and Algae and plant can grow.

Do you have any fish in the ponds? Fish waste would provide nutrient for the duckweed.to grow.

Yes, fish recently added to pond.

Additionally, pond had been used as dump for kitchen wastes for about a month. (without my knowledge I should add)

-sterling

 

[DailyLunatic]

Water hyacinth is common in your region, right?

Not only is it common, it is a nuisance. (see pic of local river)

Conflicting web information shows that Water Hyacinth, and Water Lettuce are both used as fodder for, and are toxic to, goats. Calcium Oxalate crystals in the leaves causing mouth sores and kidney damage. Some information showing is okay to use, some that it is toxic, and some that it is okay as long as limited to 30% or less.

What if any experience have others seen?

-sterling