# Does Duckweed get rid of green water?



## MantisX (Aug 25, 2004)

Does it? It sucks up all excess nutrients and when it gets thicker, it makes the light less intense. I put a lil in my 10 gallon today to see what itd do for me. Has anyone had any experiences with a plant like this combating green algae?


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## ninoboy (Jan 26, 2004)

I floated wisteria to get rid of green water and it worked perfectly. Green spot algae on the other hand is normal in a planted tank. They even appear in an established tank (on the glass usually). 

How old is the tank? Lighting wattage? Fertilizer?


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## tombsc (Nov 24, 2003)

It got rid of all the hair algae and tiny amount of slime in my tank. Not sure about green water.
I started with about 5 single plants. They reproduced to cover about 20% of the surface, all the algae went away and now all the duckweed has also gone. Not sure where.....it's a mystery. So now all I have is healthy plants and I don't have to worry about getting rid of the duckweed. roud:


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## Ibn (Nov 19, 2003)

Most likely one or more of your fish is eating it (my angels love this stuff for some reason). It has a tendency to rot away when you first put it in the tank, but once established, it's really a weed.

It grows so fast and shades too much of the light from reaching the other plants below the surface. I've used salvinia instead due to their slower growth (with duckweed, I'd have to skim the top of the tank every week, whereas salvinia was about once a month).

You can also use stem plants if you're interested in a nutrient sump. Hornwort, ambulia, and wisteria are some which belong in this category.


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## djlen (Sep 14, 2003)

What other plants do you have in the tank, and how long has it been set up?

Len


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## MantisX (Aug 25, 2004)

This tank has been set up for about 6-8 months, but I recently restarted keeping different plants about a month ago. Its a 10 gallon which includes, hairgrass(acicularis) Mayaca, Ludwigia "Cuba", Eustrella Stellatis?, Java fern on a rock, Vallisneria americana, and stargrass. I can post pictures if you like. It is growing in extremely beautiful, (at least in my eyes) I just have to get rid of this crappy green stuff. Im looking at a vortex and a tetra whisper diatom. In the meantime though, I have the duckweed in there doing what it can to get the supposed nutrients out of my water. I dont understand it. For the last week I havent dosed anything. I dunno what the hell its eating. Same thing for my plants. They are pearling and doing great but the only thing im putting in the water is c02.


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## ninoboy (Jan 26, 2004)

MantisX said:


> For the last week I havent dosed anything. I dunno what the hell its eating. Same thing for my plants. They are pearling and doing great but the only thing im putting in the water is c02.


That may as well be the problem. The plants have exhausted all the nutrients and may have grown slower. That's the time when algae kicked in. How many watts/gl of lighting you have? May need to get the macro levels up roud:


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## MantisX (Aug 25, 2004)

Hi. Its a 10 gallon wth 3.6 watts of pc lighthing via ahsupply. I thought you werent supposed to dose when green water is present? Im confused. Im not supposed to do a water change either right?


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## MantisX (Aug 25, 2004)

Here are some pictures of my current foggy situation. I dont have the best camera in the world, but you can kind of see what im dealing with.


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## ninoboy (Jan 26, 2004)

Oops, sorry. I read your post too fast and thought you said you didn't dose anything for 8 months :icon_redf 

Yes, if your plants are still growing nicely and pearling, then there should be some excess nutrients somewhere. I usually still do water changes like usual when fighting with gw. There are several ways to deal with it :
- total black out : I've never liked this option.
- Placing daphnia in the tank : provided you don't have fish in there that eat them.
- Diatom filter 
- Floating plants. I did this in the last tank I set up last month. It only took two weeks to turn my pea soup tank into clear one. I'll post my site later to show you  

Honestly speaking, I have no idea what the heck they feed on :icon_roll The last tank I set up had 0 level of PO4, ammonia, nitrite, nitrate, no fertilizer and no fish at all when it started.


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## MantisX (Aug 25, 2004)

The sad part is that I finally claimed victorious over hair algae shortly before I got this stuff. My plants outcompeted the hair algae with my help of course. Every other day id go in there and get as much as I could by hand. At first it would be back like the next day, until finally I saw a nice brown patch of it towards my pearlgrass. Victory!! Not! It wont be a victory until I get my clear water back. I have a 29 gallon that has pristinely clear water, but the ph is so high on it. No way I could use that with the rams.


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## ninoboy (Jan 26, 2004)

You have the exact algae problems I had. Started with brown algae, then hair algae and at last green water. Here it is : http://www.msnusers.com/webnino/30glhexagonjournal.msnw?Page=2

The last photo (Aug 17) actually has only a slight tint of green but basically clear of GW. The floating plants and leaves of the caurelus made green reflection to the tank. Added to that, I'm a terrible photographer. I haven't updated it yet but on Aug.21. the whole tank is totally cleared. I took out all the floating plants (wisteria) and trim the damn aponogeton.


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## MantisX (Aug 25, 2004)

hmm maybe this duckweed can do the trick then. I cant get my hands on any wisteria at the moment, but hopefully I will win either a magnum or vortex and at least get my water clear so I can get back to work. I know its not hurting anything, its just annoying to only see my fish when I feed them and I can barely see the plants in the back anymore.


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## ninoboy (Jan 26, 2004)

I'm pretty sure it would work. I got the idea from a green water article and the author's favorite method is to use floating plants and daphnia. He actually mentioned water sprite, wisteria, duckweed and another one I can't recall. According to him, diatom filter is fine but there is a chance of the green water coming back since you're not actually clear it by reaching the tank balance. I believe he also mentioned about doing water changes every 3 days just in case there are some excessive nutrient build up that cause it.


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## pufferfreak (Oct 19, 2003)

Whenever I had greenwater, I just did about 505 water changes every day for a week, after 2 weeks it went away.


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## MantisX (Aug 25, 2004)

Eureka!! magnum 250 arrived today and I cleared my stuff up. And I got it right the first time thanks to this awesome forum. Now I can adjust my water parameters and at least see whats going on. Thanks guys and gals. Im looking forward to actually seeing my plants fill in.


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## Momotaro (Feb 21, 2003)

Very good Mantis! Glad to see crystal clear, sparkling water!

I think you should follow up by getting out your test kits and finding a fertilizing regime that will start to help that aquarium find a balance and maintain that clear water. The Magnum did a great job treating the symptom, now you'll have to be persistent and decode what caused the problem in the first place. we have all done it, and I am sure you will be able to do it easily as well!  

Mike


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## MantisX (Aug 25, 2004)

I think im on the verge of finding it already. Ironically after the water cleared, I took a peek at my substrate towards the back and what do I see? A laterite ball that seems to have been dug up by my ramshorn snails. I dont know if that was the whole problem but I bet it was part of it. I thought I buried it deep enough where they couldnt get to it. I pried it up and reinserted it under my Ludwigia "cuba". I am also going to run a full test on the water tonight around lights out time and see if anything changed.

Does diatom suck slime coat out of the water too? If so how long till it reestablishes?


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