# I can't grow duckweed.



## Bunfoo (Jan 14, 2012)

It won't grow at all! I've tried it all sorts of ways. indoors, outdoors, flow, no flor, sun, shade, warm, cool. Clean water, tank water, ground water. no matter what it just won't grow. 

I actually want to grow some to work more green into my turtle's diet, and I've spent weeks trying to grow it with no luck. 

Anyone know anything that might help it along? Maybe something I'm missing? What it prefer slower, still, or fast flowing water? full sun, partial sun, shade? Trying to find the right combination to get it to grow is not going well. 

also, I bought an 8" water lettuce, which died, but not before sending out a lot of babies. but these babies never grow. they multiply like rabbits but stay the size of a quarter?


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## Monster Fish (Mar 15, 2011)

Duckweed loves water high in nitrates and other ferts. It also does better with high light and still water.


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## Bunfoo (Jan 14, 2012)

I've tried growing it in water with nitrates at 10, 15, and 20 ppm. I suppose it could be i'm missing some other element? I'd be feeding it to the turtles so I want it to be pretty much chemical-free..Hmm..


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## eco (Feb 23, 2012)

Having fish in an outside pond should supply enough ferts and light for duckweed. Works like crazy for me


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## Monster Fish (Mar 15, 2011)

Bunfoo said:


> I've tried growing it in water with nitrates at 10, 15, and 20 ppm. I suppose it could be i'm missing some other element? I'd be feeding it to the turtles so I want it to be pretty much chemical-free..Hmm..


You'll also need potassium and phosphates.


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## BS87 (Apr 9, 2012)

Is the water surface agitated? It barely held on in my 40B with decent surface agitation, but I filled a 5G bucket with water, threw in a handful of fish food pellets, and about 15 duckweed plants and put it on my porch.

In a week the bucket was choked full of the stuff.


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## Bunfoo (Jan 14, 2012)

eco said:


> Having fish in an outside pond should supply enough ferts and light for duckweed. Works like crazy for me


I've tried growing it in my container pond that's got guppies, tadpoles. it grows other plants just fine, like water lettuce, water cress, parrot's feather, hyacinth, etc. Just the duckweed won't grow! At least, not very fast at all. It grows just enough to seem like it's the same amount all the time.  

(not sure how to do multiple quotes, sorry!)

@ Monster fish

My water has both, as well as magnesium, which I've heard can be a problem in growing duckweed if you don't have enough? 

@BS87

I've tried growing in fast/med/slow currents as well as still water. right now it's in my container pond which has no flow at all other than what the wind/fish/temperature causes to move. I may try throwing some in a bucket with some dirts and a few fish pellet and see if an overload of nutrients will speed it up any...


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## Monster Fish (Mar 15, 2011)

Try growing just the duckweed by itself in a container with some fish pellets. I think it might be getting out-competed by the other plants.


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## Bunfoo (Jan 14, 2012)

Monster Fish said:


> Try growing just the duckweed by itself in a container with some fish pellets. I think it might be getting out-competed by the other plants.



I'll give it a shot.  Thanks!


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## GuppyGuppyGuppyGuppyGuppy (Feb 11, 2012)

Step 1: Acquire a water holding device.

Step 2: Apply duckweed

Step 3: Wait a month

Step 4: Harvest duckweed

If you try really hard, it won't work. IMO just set up a 5g with some gravel, throw a few plants in (like anacharis or hardy things you have in other tanks) and add a few fish like guppies. Do whatever you want to it, or nothing at all. You can overfeed, not feed at all, either works. When my water got mucky the duckweed stopped growing, but when it was nice and clean it grew well. So keep the water clean (by that I mean clear, not green, no algae) and then add some duckweed and wait.

In California around this time, guppies and everything else you want should be fine outside in a 5g for a few months. SoCal is even better than NorCal, lucky for you. If you live nearest the ocean in Inland Empire, then you should be able to everything other there for the entire year as long as it doesn't get below 50F at night. My guppies survived 40F nights, 100F days at the most extreme. The water stayed about 55F to 85F at the extremes. No food, mucky water, still reproduced.

Like seriously, if your friend has a pond on their property that they will let you put some duckweed in, then throw some in and go back to collect it in like three months lol.

ALSO, it may be the source of where you're getting your duckweed, and there may be different kinds of duckweed. Get duckweed from a few different fish stores or hobbyists and try that out.

Not sure if it matters or if you've tried it, but maybe dechlorinate the water if you haven't already. If you're using tap water, it may be something in it. Try distilled or bottled water from the grocery store.


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## BDoss1985 (Sep 15, 2011)

I grow it for my RES also, and I noticed something with hood off my 55 g community tank I had to remove the duckweed weekly for months, I put the hood back on a few weeks ago and almost no growth. I can cover the whole top of the turtle tank with duckweed and before the day is done it's gone and that's just 2 turtles about 5 inches.


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## TamraF (Sep 9, 2012)

*Trace Elements Needed for Duckweed*

Bunfoo, try throwing in a spadeful of dirt or appropriate amount for your container. This will provide trace elements that all plants need. I do this routinely when growing out duckweed in kiddie pools. Works like a charm. www.DuckweedGardening.com


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## kevbshields (Mar 4, 2004)

I wish I had this problem. Used to I couldn't grow it for anything. I had to throw out about 10 net fulls of the stuff; in less than 5 days it had overrun my Xiphophorus tank. I'm concerned about lowering nitrate levels as how this will impact my swords, Vals & Sag . . . though they have read consistently low lately. Anyhow, good luck on the duckweed; you'll wish you'd have never started growing it soon enough.


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## Diana (Jan 14, 2010)

Water Lettuce:
Does not like too high humidity around the leaves. No droplets of water on the leaves. 

I grow it in 2 places the best:
I have an outdoor pond, and it grows all summer, but frosts in the winter. Some surface movement, fair amount of shade, but it is bright shade, not dense. 
I have a pond and several aquariums in a greenhouse. Very bright light, but not direct sun. Low water movement is best. In high water movement the Water Lettuce gets swept into a corner. 

Fertilizing on all these set ups is fairly low. NO3 kept under 20 ppm, but generally some nutrients going in from fish food, fallen leaves, or dosing. Just not high levels. 

In a covered aquarium Water Lettuce never grew into the 'lettuce' look, the vertical growth, except in one tank where the sun came in, and the Water Lettuce grew out the back of the tank. Very quickly outgrew that limited space. 

It can grow really fast. Once it got going in my greenhouse pond it really took off. About a month to go from the flat aquarium style of growth to some vertical growth, then another month to almost cover the pond. I started with about a dozen little plants. The pond is a free-form with lots of curves, and fits into an area of 4' x 6', so is not large. It is now about 75% or more covered with Water Lettuce. 

I have a lot of duckweed. 
Reasonable light, outdoor pond, greenhouse pond, all the mid-light aquariums. Not the low light tanks. 
Low water movement. 
Does not seem to like ammonia (I am cycling a tank and over half the duckweed has died) and does not like salt (I have tried it in my low end brackish tank).


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## Indian fern (Jul 16, 2012)

I just dumped some in my outdoor fountain in a sunny area, and in weeks they covered it fast. They are a MENACE!


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## Bunfoo (Jan 14, 2012)

I do live in california but I'm at a high altitude so my weather is a bit more like up north- around this time I have 80-90F days and 40-50F nights. In a few weeks we will be back in the mid 20's F round the clock, in which case I'll take the container ponds into the garage. 

I have tried growing it in containers with dirt, and with no dirt, with no noticeable difference. I went ahead and threw some in a container with some pond food pellets and a little dirt a few days ago and haven't noticed any growth. 

The water lettuce also has no vertical growth. there isn't any water current and I am growing in both full sun and shade with no noticeable difference. My water hyacinth also grows extremely compact despite being grown in the shade. 

The container pond has about 70 guppies(fry) right now and roughly 10 tadpoles, and some snails. It's got anubias, cryptocoryne, amazon swords, java moss, and some vals below the surface, with water hyacinth, water lettuce, parrot's feather, and of course some of the duck weed I have been tying to grow. The water is always crystal clean and has very little algae growth, but nitrates remain at 15-20ppm. Ammonia is at 0 every time I've tested. 

i also have some in a small tupperware (the kind used to store cakes) with a handful of dirt, and some fish food pellets and flakes. it is in full sun in the morning and evening and shaded during the hottest parts of the day. No change yet, but hopefully soon. 

If I can't get it to grow soon I may just switch and see if i have better luck with watercress.


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## Bunfoo (Jan 14, 2012)

Here is the main little container

http://i45.tinypic.com/ezjyut.jpg

1. Extremely compact growth of water hyacinth. The tall ones were added a few days ago. The short, compact ones are all offshoots of a single one I bought that eventually sloughed it's roots and completely perished. Have not been able to get the hyacinth to grow any taller in any conditions. It is healthy and continues to make runners, just doesn't grow taller. 

2. all duckweed that was added a few days ago. no noticeable growth since i put a lot in there in the first place. 

3. water hyacinth that i added a few days ago. I expect it to make one or two runners and then probably die off, as they always seem to. 

4. very flat water lettuce. Never gets bigger than a dime or quarter but continues to propagate in all conditions.


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## spyke (Oct 14, 2010)

Is this thread for real? I can't grow duckweed? If you can't grow duckweed you should get out of the hobby...seriously. That's like saying I'm trying really hard to get herpes. Its easy to get, can happen unknowingly, spreads like wildfire, and for most, is impossible to get rid of once established. I hate to sound so blunt. But why would you want duckweed? It's like the plague!


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## Bunfoo (Jan 14, 2012)

spyke said:


> Is this thread for real? I can't grow duckweed? If you can't grow duckweed you should get out of the hobby...seriously. That's like saying I'm trying really hard to get herpes. Its easy to get, can happen unknowingly, spreads like wildfire, and for most, is impossible to get rid of once established. I hate to sound so blunt. But why would you want duckweed? It's like the plague!


So I've heard.  I want to grow it to feed to some of my animals, mostly my turtles, goldfish, rabbits , chickens, ducks and my rats who all enjoy snacking on it. I figure it's a good way to grow some extra fodder for the animals and make use of all the collected rainwater I never use. I also happen to think it looks cute and adds a certain charm when it's controlled...

I can grow everything else just fine- it all grows like weeds for me. But the only thing that just doesn't grow is the duckweed! 

I'm sure it's definately like the plauge in tanks- I wouldn't want this stuff clogging my filter and blocking all my light (which is why I don't try to grow it in my tanks.. ) but my tubs full of water are another story!


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## pinoyghost2 (Feb 13, 2012)

Good grief, I just put a few tiny plants in one of my shrimp tanks and turn the light on and left it.....a few weeks later its 2 inch thick carpet! 

Ive tried drying it out, feeding it to my goldfish, and still it comes back to life :icon_roll I am convinced it has a life of its own and can survive anything, anyone, and it KNOWS when you are trying to scoop it up, it drops to the bottom of the tank, hides behide the filter, hangs onto your other plants till you go away in frustration! Maybe I should package it all up and ship it to YOU! DUCKWEED KILLER....


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## tomfromstlouis (Apr 2, 2012)

Bunfoo said:


> ...I can grow everything else just fine- it all grows like weeds for me. But the only thing that just doesn't grow is the duckweed!...



Is it okay to laugh? I find this whole thing so funny. Thanks for making this place even more fun.

Bunfoo is a pretty good name. "Duckweed Killer" though, is priceless.


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## ajlee613 (Aug 24, 2012)

haha for some reason i found the title of this post really comical.


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## sayurasem (Jun 17, 2011)

I think you are the luckiest person in this hobby!


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## SpecGrrl (Jul 26, 2012)

pinoyghost2 said:


> Good grief, I just put a few tiny plants in one of my shrimp tanks and turn the light on and left it.....a few weeks later its 2 inch thick carpet!
> 
> Ive tried drying it out, feeding it to my goldfish, and still it comes back to life :icon_roll I am convinced it has a life of its own and can survive anything, anyone, and it KNOWS when you are trying to scoop it up, it drops to the bottom of the tank, hides behide the filter, hangs onto your other plants till you go away in frustration! Maybe I should package it all up and ship it to YOU! DUCKWEED KILLER....


Omgoodness OP is a duckweed null!

Can we create a vaccine?

Ae'd make millions!

Fish and Wildlfe could hire him to wade in rivers, slaying rafts of duckweed or at least rendering them infertile!

Duckweed contraceptive!


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## TamraF (Sep 9, 2012)

*Menace???*

Manilla, harvest your duckweed and use as green mulch in the garden or around your fruit trees. Use it in compost. It's like free fertilizer if you pull it out of your water column. Otherwise, it will die, sink to the bottom and start the cycle all over again. A group of researchers and entrepreneurs are working to commercialize its production- International Lemna Association. Go to www.DuckweedGardening.com and read over 70 ways to utilize it...


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## Steve001 (Feb 26, 2011)

Bunfoo said:


> I've tried growing it in my container pond that's got guppies, tadpoles. it grows other plants just fine, like water lettuce, water cress, parrot's feather, hyacinth, etc. Just the duckweed won't grow! At least, not very fast at all. It grows just enough to seem like it's the same amount all the time.
> 
> (not sure how to do multiple quotes, sorry!)


Multi quotes is simple to do. Do you see that icon *"**+* in the lower right of the window. Click that for each person you want to multi quote.

Does duckweed grow well where you live ?


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## acitydweller (Dec 28, 2011)

To me it looks like its possibly not getting the full light spectrum. does the one in the photo get direct sunlight?


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## Diana (Jan 14, 2010)

What is the temperature of the air? Sounds like these are getting too cold at night. 

You might try covering the container, making it like a mini greenhouse. See if that conserves enough heat to help out. 

Around here I have a hard time growing Water Hyacinth and Water Lettuce in the milder Spring and Fall, and they both die in the winter. I am having much greater success in my greenhouse. In the nearby rivers Water Hyacinth can survive well enough to grow again in the Spring, to the point that they are a menace to boating in some of the smaller channels. 

I have grown duckweed in most of my aquariums, but it grows better with more light. The lowest light tanks do not support it very well. It does not thrive in my brackish water tank. Are you salting the water?


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## Bunfoo (Jan 14, 2012)

The one in the photo gets direct sunlight up until 12pm and then it gets about half shaded. If I put it in full sun everything burns and dies. Even the land gardens here are covered in shade cloth to prevent the sun from toasting everything, and because we have high winds pretty much every day the ground gets dried out pretty fast. 

No salt in the water, it's just straight rainwater, no additives in it at all. 

I have never seen duckweed in any of the rivers/lakes/ponds around here so it probably does not grow well (it does stay around 22-25F for a pretty long period in the winter) right now it is about 45F on a low night and 55F on an average night I think. I have been trying to grow duckweed since spring. I know it DOES grow at a plant nursery which is at a higher elevation than I am at- that is where I usually get it. I go there and they let me scoop out as much as i please for free from the hyacinth/lettuce ponds. They always have thick mats of it. They tell me they just use rainwater or well water for the container ponds too, so not sure why mine are different since we share the same kind of water I believe. 

I have noticed some(read: a very little) growth on the duckweed in the small container that I threw some pond pellets in at you guy's advice. I don't know why it works with the pellets but doesn't work with fish/flakes/dirt/etc but it appears that it does! The duckweed in the pink pond has slowly died back a little though. The duckweed in the green pond (which gets sunlight all day) burned up mostly. A few little bits of it have lived and hopefully have adjusted to the sun and will maybe start growing. 

I threw a bit in the turtle's tanks and of course this morning could not find a single tiny spec of it anywhere. :icon_cry:


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## spyke (Oct 14, 2010)

SpecGrrl said:


> Omgoodness OP is a duckweed null!
> 
> Can we create a vaccine?
> 
> ...


lol!


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## pinoyghost2 (Feb 13, 2012)

Bunfoo in all honesty we are not trying to be nasty and hurtful in any way, so please don't take this personally! We have all had horrible experiences in trying to get RID of this invasive plant, so when someone says I can't grow DUCKWEED its like saying I can't boil an egg 

Its probably right that its the temp thing that's doing it, fluctuating between high temps in the daytime and low ones at night, it doesn't like it. My temps are kept at a steady 70F and it grows like no tomorrow.

Can you not grow it indoors? Use a big plastic pond container or one of those big deep round plastic things that hold kids toys from Walmart? 

You could just put it under a light and stick an airstone in the container and see if that works for you.


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## Bunfoo (Jan 14, 2012)

pinoyghost2 said:


> Bunfoo in all honesty we are not trying to be nasty and hurtful in any way, so please don't take this personally! We have all had horrible experiences in trying to get RID of this invasive plant, so when someone says I can't grow DUCKWEED its like saying I can't boil an egg
> 
> Its probably right that its the temp thing that's doing it, fluctuating between high temps in the daytime and low ones at night, it doesn't like it. My temps are kept at a steady 70F and it grows like no tomorrow.
> 
> ...


haha, no worries, i giggled at quite a few of these posts too!

Unfortunately everything in my house is electric and there is only one electric company here that basically has a monopoly. My electric bill in constantly higher than $250 and that's with minimal electricity usage. I literally can't afford to set up lights indoors, and sadly none of my windows other than those in the living room get sun (talk about bad placement? cant even watch movies!) and there is only two windows in the garage, both of which don't provide any sun.

earlier this summer we had temps in the 90F in the day and 80F at night, still wouldn't grow! The one in the container with pond pellets is growing though. If it grows enough I will buy a couple kiddie pools and try growing a lot before it gets too cold to grow entirely.


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## Steve001 (Feb 26, 2011)

I agree it's the swing in temperature causing the problem.


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## Bunfoo (Jan 14, 2012)

You were right! 

I was doing more research into why the duckweed/lettuce/etc either wont grow or grows slow/short. Temperature is definitely a player in this. From what I can tell it is just too cold at night to try growing these plants outdoors. 

Does anyone know if these will survive the winter as long as the water does not freeze? I can move them inside and hook up a heater to the container and set it to about 50F. Would that be enough for the plants to make it? There's no direct sunlight in the garage either so they'd have to make do with short periods of indirect light...

I bought one of the plastic wine barrels from home depot and switched over to that. It's a little thicker and it's black so I'm hoping it will hold in heat better than the pink tub, and I will throw some loose plastic on top of the pond every night to help keep in heat.


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## SpecGrrl (Jul 26, 2012)

Bunfoo said:


> You were right!
> 
> I was doing more research into why the duckweed/lettuce/etc either wont grow or grows slow/short. Temperature is definitely a player in this. From what I can tell it is just too cold at night to try growing these plants outdoors.
> 
> ...


I congratulate you!

Happy feeding!


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## secuono (Nov 19, 2009)

Get a wide bucket, fill it with fertilizer/duck/chicken poop or feed. Place in direct full sun, let the water warm up first and then add the duckweed. But if the duckweed is used to indoor light, the direct sun will burn it and it'll need time to grow back.


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## villandra (Sep 29, 2017)

OK, my duckweed in a plastic container of water with some urine under one of those screwin flourescents that wasn't growing now has water from the fish tank, a little plant fertilizer, a little aquarium plant fertilizer, and a few fish pellets. We'll see.


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## Surf (Jun 13, 2017)

> No salt in the water, it's just straight rainwater, no additives in it at all.


I don't know why I didn't see this post earlier. I did once hive duck weed die off. It was caused by a nutrient deficiency. Plants need nutrients. And if your are using rain water, which has none, no plant will grow. 

Plants need the following elements in the water:

Nitrogen (N), Phosphorous (P), Potassium (K), Calcium (Ca), Magnesium (Mg), Sulfur )S) These are known as macro nutrients because plants use more of these than most other nutrients combined. They are typically in the water at a concentration of at least 1ppm (Parts Per Million)

The remaining nutrients are called micros and are typically present in the water at PPB (Parts Per Billion Levels). The are Iron (Fe), Chlorine (Cl), Boron (B), Magnanese (Mn), Zinc (Zn)), Copper (Cu), Molybdenum (Mo), Nickel (Ni).

If you are short in just one nutrient the plant may die. Many people put soil in aquarium because it has nutrients. It does but it may have all, some, or missing multiple nutrients. Same goes for urine and fish food. There is no guarantee that whatever you use has enough to grow plants. 

In fact most fertilizers don't have calcium, Chlorine, and Nickel. They may be abundant in soil but not in an aquarium or bucket of water. Many People fertilize their tanks with NPK and a micro nutrient fertilizer such as CSM+B, and it works if the water has enough calcium, sulfur, and chlorine. But sometimes tap water doesn't. If that is the case a GH booster such as Sachem Equilibrium is used to add calcium and sulfur to the NPK, CSM+B mix. Very few people need to add Chlorine (very abundant) and nickel (only needed in extremely small quantities.

One other thing that is often done that does help is a water change. Normally in an aquarium minerals tend to build up making the water increasingly hard. fish food and fertilizers are a major source of these minerals. If these minerals are not removed the water may become toxic to plants and animals. In many aquarium between 20 to 50% of the water is replaced weekly to prevent mineral build up. Also the new water does add some nutrients which will also help. 

So if you take rain water (pure water) and macro and micro nutrients and then add take steps to insure no nutrient is missing, Duck week will grow very well.


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## Surf (Jun 13, 2017)

> Does anyone know if these will survive the winter as long as the water does not freeze?


I put some outside in a shaded area in bottle because at the time it wasn't doing well in my aquarium. I then fixed the nutrient deficiency in my aquarium and forgot about the bottle outside. A year and a half later there was still live duckweed in it. In the winter were I live it rarely freezes at night and quickly warms up during the day. Summer temps are typically in the 80s with occasional heat waves into the high 90's. The bottle was in the shade to the sun wouldn't cook it and kill the duck weed.




> I agree it's the swing in temperature causing the problem.


It grows wild in a nearby park and seasonal temperature changes don't kill it as long as it doesn't freeze, gets too hot, or dries out. It definitely does grow faster between 60 and 80 degrees but will still grow in higher and lower temperatures. Just not as fast.


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