Duckweed Harvest

[GaryD]

Hi,

Today, we conducted our first duckweed harvest since we established our new system which includes a duckweed tank.

1. A thick mat of duckweed on the water surface.
2. Today's harvest.
3. We put the duckweed into small plastic moulds.
4. .....and then put into the freezer.
5. The duckweed tank following the harvest. We simply replace the cold frame and let the duckweed do its thing again.

The frozen duckweed biscuits are taken out as they are required. We simply snap off what we want and float it on the surface of the fish tank. The fish simply help themselves as the duckweed biscuit melts.

No, the large plastic container in the freezer is not Murray's lunch.....it's our winter stock of frozen Black Soldier Fly larvae.

Gary.

[fishfood]

Gary whats the 3 black pipes going to or from the duckweed tank arent you running it with the fish system

[anniefish]

Hi Gary,
Roughly how long does one of the duck weed patties last? I know it would depend on how many fish you have. Mrs D must be understanding, having duckweed and black fly larvae in the freezer just watch she doesn't get creative in the kitchen!!
Anniefish

[GaryD]

Hi Annie,

It does depend on how many fish are eating it. I suggest when feeding anything that you begin with small quantities and wait for the fish to clean it up before they get more.

Several species (mostly the omnivores) will eat duckweed but they may take a while to get used to it.

That particular freezer is in my shed. I experienced Navy cooking for six years, so I've eaten worse things than BSF larvae and duckweed.

Gary

[GaryD]

Hi FF,

Two of the pipes are drain lines from the satellite pots and the third one is the nutrient supply line.

Here's why we did it.......

I originally set the system up so that it would operate off of the pump that feeds the grow beds but I decided the pumping cycle didn't quite suit this system.

I've used a separate 20 watt pump to feed the satellite pots. It operates off an electric timer and runs on a 15 minutes on 15 minutes off cycle through the day and a 15/45 cycle during the night. I placed the pump in the duckweed tank and the water drains back into the same tank.

Gary

[GaryD]

Hi,

During recent weeks, I've been conducting regular harvests of duckweed from the 500 litre duckweed tank attached to my system.

I've found that the easiest way to store duckweed is to freeze it. It can be dried....and that would be the logical way to go if using very large quantities.....but freezing is perfect for the backyard fish farmer. It retains its vitamin content and you can store a lot of the stuff in a small space.

We place the freshly harvested duckweed in small plastic containers before freezing it. After freezing, we turn the 'biscuits' of duckweed out of their little moulds and place them in a plastic bag.

To feed the duckweed out, I take a biscuit and tap it with a small hammer to break it into several pieces. The pieces are just thrown into the tank where the fish attack the pieces of duckweed......pushing ithem back and forth across the tank.

Fresh duckweed can get churned up in the water and find its way into the pump. I've discovered that feeding frozen duckweed tends to avoid this problem.

Gary

[wey2go]

Anybody has experience with: http://www.duckweed.com.au/?

[GaryD]

Hi,

Here's a glimpse inside my duckweed tank. The tiny plants have formed a thick mat. Covering the tank with a small cold frame keeps the duckweed nice and clean and keeps the temperature up in the optimum range.

I harvested this lot using a large kitchen sieve. It's currently in the freezer turning into fast fish food.


Gary

[Sunshine]

gary,

What is the "cold frame"?

[GaryD]

Hi,

The cold frame is a little mini-greenhouse arrangement that I put on the duckweed tank.

It comprises an aluminium tube frame clad with heavy duty greenhouse plastic. It keeps the wind-borne debris (dust, leaves and twigs) and cane toads out of the tank while helping to keep it warm.

You can see the cold frame in place on the tank......here. Click on the photo to enlarge.

Gary