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Old 05-11-2012, 05:21 PM   #1
wetworks
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duckweed and crypts


I have several tanks set up with only crypts growing in them. In two of my tanks I have an excess of duckweed that causes the light to be diffused by the time it reaches my crypts. The other two tanks have no duckweed; other than that the tanks are identical as to lighting, filters and all other equipment. For the last three months I have been seeing two to three times the growth in the tanks with the duckweed over those tanks that do not have the duckweed. Is there an explanation for this? Other than the duckweed all parameters and equipment are the same. (The setup up is 2x20g long and 2x39g) Can the presence of the duckweed be the reason for the growth difference? Or, is there some unknown variable that I am not considering? Please help me. Thanks in advance for your replies.
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Old 05-11-2012, 05:30 PM   #2
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Maybe the light that does make it through the duckweed is a different color. Like the duckweed is acting as a filter and the crypts find that color more to there liking's. Lol. I really don't know.
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Old 05-11-2012, 06:03 PM   #3
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So everything between the two tanks is the same? Substrate/fert dosage?

Do you have fish in one tank (lots of growth) and shrimp in the other tank (slow growth)

Only thought would be : more nutrients=more growth

-Gordon
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Old 05-11-2012, 06:11 PM   #4
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Originally Posted by gordonrichards View Post
So everything between the two tanks is the same? Substrate/fert dosage?

Do you have fish in one tank (lots of growth) and shrimp in the other tank (slow growth)

Only thought would be : more nutrients=more growth

-Gordon
Everything else is almost the same. For example int 20L #1 I have six Panda Cories, where in 20L #2 I have six Bronze Cories. The fish might not be exactly the same, but they are the same types in the same proportions in each tank. The substrate, filters, lights, and dosing regimen (including root tabs) are completely identical. The tanks are in the same room, and I have the lighting periods set up on the same timer. I do maintenance on the the same day because they are adjacent to each other. There is no temp variance between the tanks at all. And it is the same for the 29g tanks that are on the iron stands that the 20L tanks sit on. If I may have missed any info that might help me figure this out, please post what info you need and I will be happy to provide it. This offer is not just for Gordon- any member who thinks they can shine some light on the issue please feel free to comment. Thanks, Gordon, for your response.
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Old 05-11-2012, 06:36 PM   #5
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Maybe the tank with duckweed have more CO2? The duckweed hinders the gas exchange.
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Old 05-12-2012, 02:25 PM   #6
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Maybe the tank with duckweed have more CO2? The duckweed hinders the gas exchange.
That sounds really interesting. Would you please explain how that works? Is it because when the duckweed is present there is no water movement at the surface and thus no gas exchange? I am not running CO2 on these tanks, if that helps figure out how/why this works. Thanks for the reply.
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Old 05-14-2012, 06:25 AM   #7
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cryptocorynes like low light
if you see one seminar dvd of his,
amano said that there's even a place where the crypt just get 30 minutes of sunlight a day and if your crypt isnt doing well, maybe you're giving it too much light

i have water lily pots outdoor filled with crypts and Lemna gibba to reduce the sunlight


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Old 05-14-2012, 09:12 AM   #8
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I know this will sound counter intuitive but I believe the crypts are growing faster in the low light tank because they are reaching/trying to find the light. They are putting all their energy into producing larger/longer leaves so they can capture as much light on as much leaf surface area as possible to photosynthesize.

I see this happen with my zoysia grass all the time. My kids have a little playset in the yard that blocks out the sun. Underneath only gets indirect light. The grass underneath always grows faster and longer than the surrounding grass in full sun.

So the next question is why doesn't the crypts in higher light grow faster? My answer is because it doesn't have to. If nothing is blocking it's light/food source than why put more energy into growing bigger/longer leaves when it can get all it needs in a smaller package. I have a feeling it is probably storing the extra energy in it's rhizome or perhaps those crypts are more likely to send runners and give you more keikis.

Just a theory. Does it make sense?
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Old 05-14-2012, 11:29 AM   #9
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Quote:
Originally Posted by wabisabi View Post
I know this will sound counter intuitive but I believe the crypts are growing faster in the low light tank because they are reaching/trying to find the light. They are putting all their energy into producing larger/longer leaves so they can capture as much light on as much leaf surface area as possible to photosynthesize.

I see this happen with my zoysia grass all the time. My kids have a little playset in the yard that blocks out the sun. Underneath only gets indirect light. The grass underneath always grows faster and longer than the surrounding grass in full sun.

So the next question is why doesn't the crypts in higher light grow faster? My answer is because it doesn't have to. If nothing is blocking it's light/food source than why put more energy into growing bigger/longer leaves when it can get all it needs in a smaller package. I have a feeling it is probably storing the extra energy in it's rhizome or perhaps those crypts are more likely to send runners and give you more keikis.

Just a theory. Does it make sense?
+1 I had a 150w hqi over my crypt tank for about a year and all the crypts stayed short and bushy as soon as I switched it out to twin T5HO's the crypts exploded and doubled in size in about 2 weeks. Since then they have stayed that size. Based on this I agree that high light doesn't require them to get as big, C parva is a good example of this is stays really small and compact under high light bit gets long and a little leggy under lower light.

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Old 05-15-2012, 04:13 PM   #10
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Thia makes absolute sense, thanks guys! As I also noted in another post, I am having trouble with algae- specifically in the tanks I have that are not over run with duckweed. So I am probably just gonna cultivate a colony of duckweed in each of my tanks as an additional rampart against future algae issues. Funny, when I first got it (and could not get rid of it) I thought it was a huge nuisance. Now it seems like it actually fills a niche in making the closed aquarium environment into a broader and healthier ecosystem. I am actually starting to feel the same way about pond snails, too. Funny how my appreciation for something like that changes the more I learn about it. Thanks everyone for all of your posts.
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Old 05-15-2012, 04:25 PM   #11
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another thing duckweed does that hasn`t been mentioned is to purify the water, that is normalize it. I use frogbit for the same reason and I find algae is much easier to control when an external source of CO2 isn`t present. This is especially true in new tanks where algae sometimes gets the upper hand first.
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Old 05-15-2012, 05:14 PM   #12
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Do you notice the duckweed sending out longer roots.

its a sign that they are infact sucking down on excess the water column, usually nitrates. They are likely keeping the extreme water parameters under control which helps the crypts. light demands and growth behavior also would vary by the type.

Just resonating Klaus07's advise. I have floaters in all my tanks and value their benefits.
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Old 05-16-2012, 01:39 PM   #13
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Thanks everyone for your replies. I had started to change my mind about duckweed being a nuisance, but it seems like as long as I keep it out of the filter intake there are a lot of benefits. I had posted a few months ago about having an incredibly overstocked tank that was in terrific health, and I thought duckweed (and anacharis, too) was exactly the reason. My only complaint is that it gets stuck in huge clumps underneath my crypts with larger leaves (C. cordata, mostly) which is more me being nit-picky since it does no actual harm or damage to anything. Long live duckweed!
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Old 06-25-2012, 02:31 PM   #14
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After a bit more experimentation involving most of my tanks, I have realized that there is a fine line between having enough duckweed and having too much. In two of my tanks my duckweed ran out of control and caused a bit of crypt melt as well as holes in the leaves of my anubias and java ferns. In my other tanks I have either severely thinned the duckweed or removed it altogether. The duckweed does help remove algae, but it also, as noted in the conversation above, diffuses light to my crypts. Apparently too much duckweed cover depletes all of the available nutrients as well as blocking/diffusing the light, and if I let this get out of control then it can and will harm my plants. Unfortunately, this stuff grows so fast that it almost needs to be removed daily.
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Old 06-25-2012, 03:01 PM   #15
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If plants do not get enough light, a process called etiolation comes into play. As a response to deficient lighting, physiologic processes in the plant's cells promote the process where auxins are produced. Auxins cause the cells to increase dramatically in length. Thus, you end up with plants that look more spindly and elongated. You see examples of this with house plants kept in too little light or a plant that has been left, say, in a garage for awhile.
Exposure to more light, conversely will result in the return of still pasts to the chloroplast state and thus normal plant growth due to lessened auxin production.
Too much light will conversely result in shorter mor compact looking plants.
That's it in a nutshell.
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