Growing Duckweed

[Reds12]

Usually I keep duckweed in my planted tropical tank, and scoop out a bit every few days or so to give to the goldfish fry out in their pond (I guess they're not really fry anymore, but that's beside the point, lol)  I've noticed since the weather has warmed up here my duckweed growth has increased, and I recently scooped out a bunch of it and put it into the main pond to see if the fish in there would like some.  Needless to say they DEVOURED it.  Since then, every time - about once a week - I add a batch of it from my tropical tank into the pond, and since my fish out there love it so much I want to be able to keep up with that.

 

Obviously they have a voracious appetite, so I don't think I'll be able to give them as much as they want, but I'd like to be able to give it to them a few times a week.  Unfortunately, my tropical tank won't keep up with that.  I'm wondering what the best way to get the fastest growth would be?  I have a couple ideas, wondering if anyone would like to weigh in on them, or offer one better?

 

1.  add some sort of basket into the pond where it can grow and the fish can't get to it

 

2.  have a "fishless" bucket/tub outside filled with the water I siphon out of the goldfish tank - my concerns would be mosquitoes etc.  Water gets pretty warm here in the summer and from what I've seen, it really likes/grows best in warm water.

 

3.  set up some sort of water garden with a small pump to keep water moving and fertilize the water?

 

4. don't bother feeding it to them more than the tropical tank can supply

 

I know most tropical people fight to get rid of duckweed since it can be such a nuisance, but I'm sure other goldfish people like it as well since its added filtration and the fish love it so much.

 

[Justin]

I really like your first idea about the basket! I think it would have various benefits. On top of not having to transfer the duckweed from your tank to the pond several times per week, the duckweed would be grown right in the goldfish pond, which would help filter their water and absorb nitrites, ammonia, etc.

[Arctic Mama]

I think the basket is a great idea, too. I haven't ben able to float any in my goldie tank long term - they eat it too fast! So I've been scooping it out of a secondary trop plant grow out tank. But longer term, a little net or basket would be great

[Reds12]

Something like this so the duckweed stays contained, but so I could just life the tray out of the water to release the duckweed to the rest of the pond.  As long as the mesh at the bottom was small enough the fish don't get in there or end up hurting themselves.  Maybe use a small pool noodle foam thing so it would always stay at the right height to the water so I don't have to worry about water level getting too low and the plants drying up?  

 

http://www.planetnatural.com/wp-content/uploads/mesh-flat-lg.jpg

[GoldenSpoiledRotten]

I enjoy the idea of the fishless bucket. To prevent mosquitos, just add a source of agitation to the water surface. Duckweed do fine with a little agitation, so either a little 'spitter' (link) or just an airstone or two would do fine. 

[shakaho]

I have made a wide variety of floating containers for duckweed,  The one I made from window screen held up by a square of pvc pipe works well.  

 

 

I took some duckweed out of the container to get all the fish together for the picture.

 

If you use anything with holes big enough for the duckweed to go through,  I say from much experience that the fish will very quickly learn how to bump the container and shake out some duckweed.  I've filled a container I thought would work, came back a couple of hours later and found it empty and the fish all indicating that they would like me to refill their new automatic duckweed feeder.

 

I made this one from an oil drain pan in which I drilled holes in the bottom.  

 

 

The "flotation" I had on this one kept coming off, so I converted it using some irrigation tubing.  I cut a piece about an inch longer than the circumference of  container just under the rim, softened one end in hot water and pushed the other end into it.  It cools air tight and I just slip it on from the bottom.  

 

 Given that the fish can't empty them, there are two problems with floating goldfish tubs.  They provide protection for critters the the goldfish would eat.  The screen container is always loaded with snails.  Small tadpoles can get through the holes in my oil pan containers and will eventually eat all of the duckweed.  They provide a way to grow mosquito larvae in a goldfish pond.  This spring I found two fry in in two different duckweed containers.  If you want to feed duckweed to goldfish multiple times per week, you will have to cover a lot of the surface of the water with floating containers.  

 

I like to use mortar tubs from HD as duckweed ponds.  They have a great surface area and will last for years. I always cover the tubs to keep the frogs out.  Tadpoles will eat all of the duckweed.  I haven't seen mosquito larvae in a duckweed tub, but you can always use mosquito dunks if they appear.  These are perfectly safe to use. 

 

 

If you get enough rain so that the tub overflows, all of the duckweed will be on the ground.  Having observed that unpleasant happening, I put overflows in all of my duckweed tubs.  The overflow is just like the one here in post #10.  As long as the intake of the outflow pipe stays below the top of the water, the duckweed will stay in the pond.

 

If you feed the duckweed with used goldfish water, you will eventually find fry in your duckweed tub --  very healthy fry.  

 

Pond keepers agree on the best fertilizer for your duckweed -- high nitrogen organic liquid fertilizer of human origin.  While the duckweed grows faster in warm water, I have trouble keeping it alive when it gets hot.  I find it does better in shade during the summer.  Some years I have lost it completely.  When I buy some new duckweed, it grows fine in spite of the heat.  I don't know what is happening.

 

 

 

[Arctic Mama]

GREAT POST! Thank you! The pictures were super helpful, too.