Duckweed dying?

[Jarrito]

I’ve been keeping my tank for a little while now and my duckweed seems to be dying out. I had other plants but those have also died. I don’t know what’s happening the fish seem to be perfectly fine but the plants are dying out.

 

[Aiken Drum]

Plants need light, CO2 and nutrients. Being a surface plant light and CO2 wont be an issue, so that leaves nutrients.
Duckweed needs a lot of nutrients and you have a lot of duckweed.
Do you know your water parameters? Plants need nitrogen, and duckweed in an aquarium will get its nitrogen requirement from nitrate. If you have zero (or very low) nitrate it is a clear sign your duckweed is pulling all the nutrients out of the water and needs more than your fish and any fertiliser are providing. What fertilser are you using? Most all in one liquid fertiliser contain essentially zero nitrogen. If your nitrate is very low then you need to use a plant fertiliser with a good amount of nitrogen in there. NA Thrive is a good one to go for if its available where you are located (Its an American product). We have TNC Complete as our alternative in the UK. I think aquarium coop and tropica does one too. You will need to trial and error how much fertilser to dose, but i would expect multiple doses a week.
There is a thing called the "duckweed index" used in planted aqiariums. The idea is to keep a little duckweed to gauge nutrient deficiency. As said, light and CO2 wont be limiting factors to plant growth, so any deficiency in duckweed will be down to nutrients. Dose fertiliser such that the duckweed is healthy, and then you know that any other plants will be good too.

 

[seangee]

That looks like frogbit rather than duckweed. No problems there IMO duckweed is a PITA and you already have surface plants. Frogbit does not like to have its leaves wet. Splashing or dunking is fine but they should not be wet all the time. This causes them to go brown and die. The Flex has a tight fitting lid which causes condensation in the tank. You could raise the hood slightly, and if you have a cover on the feeding hatch take it off. There is a fair bit of healthy looking new growth, so just remove the dead leaves / plants - you can do this weekly with water changes.
Aquatic surface plants don't need nitrates, they use ammonia preferentially and your fish / fish food will provide that. If you do decide to fertilise use a nitrate free fertiliser such as seachem comprehensive or TNC Lite. The recommended dose is fine, or if you prefer half the recommended dose twice a week. My tanks have zero nitrates and I never add these.

 

[connorlindeman]

Thats not duckweed or frogbit.
Thats Salvnina Minima.

 

[connorlindeman]

Do you add any fertilizer?

 

[Essjay]

That happened to my salvinia several years ago. It grew well for a long time then just died. At the time it was put down to being during a heatwave and condensation dripping from the lid onto the plants, but with hindsight it is more likely lack of fertiliser that killed mine.

 

[GaryE]

I find with both frogbit and duckweed, a good measure of water quality is how long the roots become. If the tank is low in nutrients, they really stretch. I have never been able to have a tank clean enough to kill duckweed, but frogbit seems more sensitive. So your clue may not be from looking above, but from below.

I hate duckweed, but it can be a natural test kit to tell you when your maintenance regime isn't up to scratch.

 

[davros]

I got Salvina and Duckweed from a local, early my tanks life. The Salvina died off over time and the duckweed dwinded to almost nothing. The duckweed has rebounded strongly in recent months. Hard to nail the rebound down, more water changes, a few more fish, some root tabs for the other plants? My point is as long as there is some
it will likely rebound when the balance is better.

 

[Byron]

I suggest you take a very close look at your water and your light.

What type of lighting? What is the spectrum? How long is the light on each day?

Water...what are the parameters (GH, temperature being the two most important here, but pH too)? Test results for ammonia, nitrite and nitrate? Is the water municipal (city), or private well? What substances are in the water, meaning if city do they add something, or private well has it been tested professionally?

What fertilizers are you using? Are you adding salt? Any other substances going in the water?

 

[Freshyfishy]

That's Salvina minima.

I grow my duckweed by placing it in bleach.... So its SUPER hardy. I know nothing about salvina minima

 

[StevenF]

Salvinia roots only grow to about 1 to 1.5 inches long no longer. Salvinia also gets CO2 from the air and it doesn't need much light to do well. Salvinia like all other plants prefer Annonia but will if necessary use nitrate. Even with just nitrate it grows very well.Plants cannot use N2 from the air.Salvinia does well with high humidity and high light or water spray and a lot of water movement doesn't hurt it.

Your tank simply ran out of nutrients nutrients plants need are nitrogen potassium, Calcium , Magnesium, Phosphate, sulfur, chloride, iron, Manganese, boron, Zinc, Copper, molybdenum, and nickel.