Duckweed

[Sege]

Hi I am still new to the fish keeping hobby and I had a couple questions about duckweed. Any feedback would be greatly appreciated. Thanks in advance
1) What are the benefits of having duckweed in an aquarium? I have a 10 gallon tank that is filtered by a TopFin 10 and heated by a Tetra Submersible Heater recommended for 10-30 gallons. What are the benefits? Or is it just for green looks?
2) I collected duckweed from a pond very close to my house, and I put it in a plastic container filled with water and a splash of hydrogen peroxide. Does that stuff truly clean it? I want to be sure all of the parasites are out of the stuff.
3) How can I tell when the duckweed is clean? Does it look different? Do I need transfer the duckweed to a different container and do the process all over again?
4) Is it safe to just dump the duckweed into my tank when it is clean? will the hydrogen peroxide harm my tank?
5) Will the duckweed dirty up my water or can I continue doing my normal cleaning process 2x a week? (Gravel Cleaner and 20% water change.)

The fish that I have are 5 Neon Tetra, a male and female Dwarf Honey Gourami, and 1 Black Racer Nerite Snail.

Thank you so much to anyone who can help me out. I'm thinking about putting the duckweed in my aquarium, (which isn't planted,) so that my fish can have something to nibble on when they are a bit hungry in between feedings which are 2x a day. (That's enough right? Or should I have more feedings/less feedings?)

~Sege

 

[Byron]

I would not recommend using wild collected duckweed. If there are ducks using the collection site, you run a serious risk of disease (it is called duckweed because ducks love to eat it, but that is not the point; duck excrement contains the risk of transmitted disease to aquarium fish). Given that duckweed usually comes "free" from fish stores if you buy fish, plants or wood from a tank with duckweed, or it is very inexpensive, it is not worth risking the fish. Aquarium fish are able to deal with many disease pathogens that are part of their habitat, but those from temperate waters are very different, and vice versa; which is why it is so dangerous to release any aquarium inhabitants or even the water into a natural ecosystem. Hydrogen peroxide is not going to be at all effective on pathogens. Nothing is.

To the duckweed itself, it can be a useful plant. Being so fast growing/spreading, it is useful to remove ammonia and other nutrients very rapidly, and thus often used in fry tanks. Some fish that are prone to eating plants will devour it, so a good food source for mollies, rift lake mbuna, silver dollars, and similar semi-vegetarians. Most aquarists find it a nuisance and prefer more substantial floating plants, like Salvinia, or more substantial still, Water Sprite, Frogbit, Water Lettuce, or some of the stem plants grown floating (Pennywort is nice like this). Floating plants are very beneficial in any aquarium; they are fast growers so they use lots of organics and nutrients (ammonia and nitrate "sinks"), and they provide shade which most all our aquarium fish prefer over direct light.

Byron.

 

[Sege]

thanks for the advice! I didn't necessarily get this duckweed from a lake/pond, more like a decorational ditch near my yard. When I collected it I was shocked because there were tiny black bugs everywhere around it, and for that I am extremely hesitant to put it in my aquarium, as they might have laid eggs in the duckweed.
As for the practicallity you mentioned, I will most likely now go over to my LFS and ask for some there, (free and all), so thanks for mentioning that.
Also, thank you for mentioning the part about pathogens. I had heard about them before from reading up on this kind of thing, but never really knew how dangerous it could be to my fish.

I have some duckweed sitting right next to me in some water, but that won't be there for long,

Thank you for all the advice!

~Sege

 

[StevenF]

you often can find duckweed an any store that sells aquatic plant This includes stores that sell matials for a decorative outdoor pond. Sometimes they won't list it. But if you look at the plants they sell you may see some floating on top. Just bring a bottle and ask if you can have it.

pathogens are viruses, bacteria, and parasites that can trigger illness like the flue and a cold or even kill. However that said pathogens that are harmful to your fish are typically not harmful to plants. So simply letting the glass of duckweed site for a few weeks will kill most pathogens harmful to fish will have died. Frequent 90% water changes would also help clear out pathogens. Kill any snails you or other small animal you see. The frequent water changes and no animals in the jar would also eliminate nutrients duck weed needs and it may start to die. Adding a small aomount of a good fertilizer such as Seachem flourish comprehensive would keep the duck weed alive. The longer you keep it in the jar the lower the pathogen risk.

The benifits of any rapidly growing plant is that it will consume nitrates and phosphates in the water plus any excess nutrient you tank may have. This will result in cleaner healthier water. However you still need to do the regular maintenance you do now. Too much hydrogen peroxide will kill anything. The amount you use makes a difference. I would guess one or 2 drops would be all you would need in the jar.

The biggest complaint people have is that it can grow very fast and cover the tank. Using a spoon or fork you shuould remove any excess as part of your regular weekly maintenance. If you later want to remove all duckweed from the tank remove all the duckweed you can see daily until there is none in the tank.

 

[Ch4rlie]

I have had duckweed in my tanks in the past, whilst it is very true these floating plants will consume a lot of nitrate and nutrients from the water column, I found these to be too fast growing and will basically cover the entire water surface given half a chance.

In trying to get rid of the duckweed, took me about 3 weeks in total to get each and every last strand to stop the duckweed from growing and starting a whole new colony of duckweed. It is what it is, a weed.

I now have much nicer floating plants being water lettuce, MUCH easier to control and easier to take out a bunch during every water change, also I much prefer these as imho are more aesthetically pleasing and the long roots that floats down into the tank seems to be something that my shrimps and fish seem to appreciate.

Also I do absolutely concur with the others in being very careful when introducing any wild or grown plants from ponds / lakes due to the potentially harmful diseases and pathogens that could spread to your livestock.

 

[Sege]

Thanks for all the wonderful advice everyone! I will keep all of it in mind.
As for the overdose on hydrogen peroxide killing a lot of things, I used a keck lot of it in my small container full of duckweed, but it has been sitting there for about 5 (I think) days now. How long should I wait until I can be 100% sure that it is safe?
I have no problem removing large amounts of the stuff with my normal bi-weekly cleaning. I like that it is small and fast growing. And if it does become a nuisance or problem, this is my first tank, so I wouldn't have very much trouble moving up to a 20/29 gallon in the future.
For the cleansing part of duckweed- thanks for the info on how it freshens up the water. I need to lower my alkalinity and pH badly. (Alkalinity 300, pH 8.4) So I don't know if the duckweed will help but I'm hoping it will show on my test strips.
Again, thank you all for the wonderful advice! I really appreciate it.

 

[Demeter32]

Duck can be a major pain when the filter pushes it under the water and it gets sucked up/stuck to the intake. There's plenty of ways to deal with that though, I've been using styrofoam bowls cut in half and positioned under the output of HOB filters.

Not only does the duckweed in my tank do a decent job of keeping the water levels stable, it also dampens the light and gives the tank a softer tinted glow. This is both a good and bad thing, it lessens the light the plants on the bottom receive, but also seems to give the fish a sense of security as they don't seem to like intense lighting.

I started with a pinch of duckweed I received from my LPS, now I remove a couple handfuls every water change. I feed it to my Africans and the mystery snails also love to eat it.

You will have a heck of a time trying to keep in the tank, I get it all over the buckets, gravel vacs, nets, breeder baskets and my arms. It sticks to everything.

 

[StevenF]

For the cleansing part of duckweed- thanks for the info on how it freshens up the water. I need to lower my alkalinity and pH badly. (Alkalinity 300, pH 8.4) So I don't know if the duckweed will help but I'm hoping it will show on my test strips.

Plants only need about 10ppm of calcium or magnesium a week. With an alkalinity of 300 you problably have hard water. Any plants isn't going to make a big change in these numbers. The best way to lower GH and KH is to mix RO or distilled water with your tap water. to get numbers suitable for the fish in your tank.

I used a keck lot of it in my small container full of duckweed, but it has been sitting there for about 5 (I think) days now. How long should I wait until I can be 100% sure that it is safe?

There is no way to know how long it takes to be 100% sure it is safe. The only way to know is to test your water for pathogens and that requires a Lab with a lot of equipment no hobbiest has.

 

[Byron]

As for the overdose on hydrogen peroxide killing a lot of things, I used a keck lot of it in my small container full of duckweed, but it has been sitting there for about 5 (I think) days now. How long should I wait until I can be 100% sure that it is safe?

Hydrogen peroxide will never kill "everything" unless it kills the plants too...which is possible. As I said previously, with wild collected duckweed you have no way of knowing what may be on/in it. Don't use it if you value your fish and other plants.

For the cleansing part of duckweed- thanks for the info on how it freshens up the water. I need to lower my alkalinity and pH badly. (Alkalinity 300, pH 8.4) So I don't know if the duckweed will help but I'm hoping it will show on my test strips.

Not sure if you may have misunderstood this. Duckweed, like all plants, needs nutrients, and it assimilates these via the roots and leaves. Ammonia/ammonium is readily taken up, as are some other nutrients. But this has its limits. And as Steven said, plants are not going to have much effect on GH, KH and pH if these are this high.

 

[Sege]

StevenF, I actually don't have hard water, surprisingly. my results from testing my water are:
Nitrate - 0
Nitrite - 0
Hardness - 0
Alkalinity - 300
pH - 8.4

Again, haven't started up the nitrogen cycle. Trying to though