# Floating plants and the mature Walstad tank



## peridot (Feb 24, 2005)

I gather some people find it hard to maintain floating plants in a Walstad tank once it is no longer new.
I never knew that there was such a tendancy. My tank (strict Walstad with yard dirt) is 4 years old and the floaters are roaring along. Have to thin them once a week or even more often or else no light gets through to other plants. The floaters were always fairly vigorous tho' occasionally discolored a brownish tinge. Now that I maintain hardness around 5 dGH, they are all bright green and very abundant. Only added nutrients are fish food and CaCL2 to maintain hardness. 

Ignorance is bliss......

Comments? 

Peridot


----------



## Dustymac (Apr 26, 2008)

I'm definitely with you on this one. I have 3 NPTs over a year old and in 2 of them the Duckweed and Frogbit are green and lush. In the third, the leaves look a bit anemic and the roots are particularly long indicating some missing nutrient, but they have been growing like this for months.

I think people will have varying results with floating plants. Since floaters get all their nutrients from the water and air, a lot will depend on how many nutrients are in the tap water you use to replenish water lost to evaporation. Another factor would be the amount of animal life in the tank and how much the fauna is fed. I think a sparsely fed tank would likely not support floaters (and algae) nearly as much as a tank where lots of food is injected daily.

Just my two cents... might be all it's worth! 

Jim


----------



## dwalstad (Apr 14, 2006)

DustyMac and Peridot,

I'm glad to hear that you have no trouble with floating plants. That's valuable information, since floating plants are so great for algae control, etc. 

This problem, then, could be specific to my setups. I cannot keep duckweed in my tanks! I'm wondering now if the problem is metal toxicity from the high zinc levels in my well water. Hmm? 

Thanks for your input!


----------



## Dustymac (Apr 26, 2008)

Diana,
It's interesting that you should bring that up. I almost lost Duckweed completely in two of my tanks while the Frogbit growing among it was thriving. This happened last summer when adding evaporative makeup water was the least frequent. I didn't do any extensive water analysis, but from the evidence I witnessed, it seemed that Duckweed may have had a nutrient requirement unique among the species in my tanks, and the deficiency has since been alleviated. I didn't imagine it could be from some sort of weakness to heavy metals.

What do you think? Are both hypotheses valid? And how would you design an experiment to find the answer?

Jim


----------



## dwalstad (Apr 14, 2006)

Dustymac said:


> Diana,
> It's interesting that you should bring that up. I almost lost Duckweed completely in two of my tanks while the Frogbit growing among it was thriving. This happened last summer when adding evaporative makeup water was the least frequent. I didn't do any extensive water analysis, but from the evidence I witnessed, it seemed that Duckweed may have had a nutrient requirement unique among the species in my tanks, and the deficiency has since been alleviated. I didn't imagine it could be from some sort of weakness to heavy metals.
> 
> What do you think? Are both hypotheses valid? And how would you design an experiment to find the answer?
> ...


Hello Jim,

I'm not having any luck with FrogBit or Water Sprite, either. My Water Sprite that is planted in soil and can get enough iron does fine.

I believe that my problem may (or may not be) related to yours. When I have more spare time (Ha!), I may investigate this.

I think that my problem boils down to iron deficiency brought on by excessive zinc. The zinc in my well water competes with iron uptake such that my plants are overloaded with zinc, which causes iron deficiency. The chemical analysees of my aquarium plants (plants were found to contain excessive zinc but minimal iron) suggest this.

To test this, some day I'll add chelated iron to the water and see what happens.

For your situation, it could be that the FrogBit has a better root system for extracting water iron and other nutrients than puny Duckweed. Or that allelopathy is involved. To test this, you could add chelated iron to the water.


----------



## peridot (Feb 24, 2005)

How would my water source tie into this? I use RO water with added epsom salts and CaCl2 for hardness (reason for RO is that is what we have coming out of the tap; our well is contaminated with sea water). So no zinc to interfer with iron uptake?


----------



## PaulNorth (Jan 17, 2009)

> I think that my problem boils down to iron deficiency brought on by excessive zinc. The zinc in my well water competes with iron uptake such that my plants are overloaded with zinc, which causes iron deficiency.


This is very interesting, Diana - when you've a moment, can you go into a bit more on the physiology/biochemistry involved?

On a side note, I really love floating plants, and hope I can get them going well in my 10 gallon. I tried duckweed which did well - too well, in fact, crazy stuff - and am adding hornwort, possibly water sprite, in addition to some parrot's feather for an emergent species. Anyone successful with Phyllanthus fluitans, "Red Root Floater?"


----------



## colinsk (Dec 29, 2008)

peridot said:


> How would my water source tie into this? I use RO water with added epsom salts and CaCl2 for hardness (reason for RO is that is what we have coming out of the tap; our well is contaminated with sea water). So no zinc to interfer with iron uptake?


Make sure you have a source of carbonates in the system. It will help buffer pH swings and some plants can utilize the carbon from it. You will have to decide if you want to have a slow reserve of carbonates in the gravel like oyster shell or if you want to add CaCO3 (chalk) to your RO water. I would do both.


----------



## dwalstad (Apr 14, 2006)

PaulNorth said:


> On a side note, I really love floating plants, and hope I can get them going well in my 10 gallon. I tried duckweed which did well - too well, in fact, crazy stuff
> 
> 
> > I would not discriminate against *any* plant that does well, especially when you have a new tank setup. If it grows well, then it is removing ammonia, etc and helping your new tank get established. In this situation (new tank with ammonia problems), I would consider duckweed a big help.


----------



## dwalstad (Apr 14, 2006)

PaulNorth said:


> On a side note, I really love floating plants, and hope I can get them going well in my 10 gallon. I tried duckweed which did well - too well, in fact, crazy stuff
> 
> 
> > I would not discriminate against *any* plant that does well, especially when you have a new tank setup. If it grows well, then it is removing ammonia, etc and helping your new tank get established. In this situation (new tank with ammonia problems), I would consider duckweed a big help.


----------



## bartoli (May 8, 2006)

dwalstad said:


> I think that my problem boils down to iron deficiency brought on by excessive zinc. The zinc in my well water competes with iron uptake such that my plants are overloaded with zinc, which causes iron deficiency. The chemical analysees of my aquarium plants (plants were found to contain excessive zinc but minimal iron) suggest this.
> 
> To test this, some day I'll add chelated iron to the water and see what happens.


Hi Diana,

If the tank has UV sterilizer, how about testing the tank water to see if there is sufficient iron available?


----------



## dwalstad (Apr 14, 2006)

bartoli said:


> Hi Diana,
> 
> If the tank has UV sterilizer, how about testing the tank water to see if there is sufficient iron available?


I have tested water in the past (before UV sterilizers) and not measured any iron. However, that may not answer the question. The plants, bacteria, etc can drain it from the water to meet their needs such that there's never any measureable iron in the water.

This has been a long-standing puzzle.


----------



## bartoli (May 8, 2006)

I too had tested zero iron for a tank that was not using a UV sterilizer. I took that to mean all the available iron had been absorbed by the plants.

In your situation, if zinc was indeed competing with iron for the plant uptake and therefore caused iron deficiency, all those left over iron would remain in the water unless they had been oxidated by the UV sterilizer. Or the UV had oxidated those iron before the plants had a chance to absorb them.


----------



## PaulNorth (Jan 17, 2009)

dwalstad said:


> PaulNorth said:
> 
> 
> > On a side note, I really love floating plants, and hope I can get them going well in my 10 gallon. I tried duckweed which did well - too well, in fact, crazy stuff
> ...


Hi Diana - just saw the reply, thanks.

What was happening was it was gathering in the high-leaves of many plants I thought needed more light - the Wisteria, which was already troubled, my L. repens. I am getting some hornwort in, and was hoping it can accomplish both rapid growth and a more "integrated" clump, so it wouldn't choke off light by gathering in the web of leaves of other plants. This was my reasoning, anyway.

Happy to report that it appears the ammonia issue has settled down, and with some platies in the tank, even my brown diatom is on the wane.

Further, in general, it just seems plant life has turned a healthier corner. I also added in several stems of L. aromatica. Too early to tell how they'll fare, but I figured that at least in the short term, as fast growers in my 20H, I could expect some filter action - even if short term - and these L. aromatica were intended to be at least sacrificial lambs, in a way and at best, long-term citizens.

Sunset hygro is definitely growing well, xmass moss has developed good mass, corymbosa no longer melting and definitely both growing new leaves, mature leaves look like their sustaining themselves well, najas growing really well, crypts expanding, hygro difformis is undergoing a leaf structure morph change, generally looking much healthier. I am knocking on some serious wood, here.

Many thanks for all your help, Diana. If my nerves hit early, I am now very keen to see this tank grow out, relatively untended. Only regime is 10 hours of light, feeding 2x daily.


----------



## Dustymac (Apr 26, 2008)

bartoli said:


> In your situation, if zinc was indeed competing with iron for the plant uptake and therefore caused iron deficiency, all those left over iron would remain in the water unless they had been oxidated by the UV sterilizer. Or the UV had oxidated those iron before the plants had a chance to absorb them.


 I never thought UV sterilizers could impact plant growth. In my case, UV sterilizers were installed on 3 of the 4 NPTs within the last 6 months. As a result, there has been no perceptible difference on floating plant growth. Then again, I don't think there is a problem with other metals in the tap water, but I couldn't say for sure.

Isn't this hobby interesting!


----------



## dwalstad (Apr 14, 2006)

PaulNorth said:


> Further, in general, it just seems plant life has turned a healthier corner. Only regime is 10 hours of light, feeding 2x daily.


Sounds good. Keep your fish well-fed, and your plants will be happy too!


----------



## mommyeireanne (Oct 24, 2007)

I too have lost my duckweed. I have had a UV filter for 15 months, had it in the old 20g. I grew duckweed there and in the 10g sans UV. I cannibalized both tanks to set up the new 75g in Oct '08. The duckweed grew for about a month and stopped. At about 6 weeks it began dying off. I couldn't believe it. I used the same exact dirt for the 75g as the 20g (same bag even, left over in the garage, and same pebble topper). I add K in the form of "No Salt" every few months and fishfood. I have noticed in the last few weeks, that my Amazon sword is yellowing and not looking happy. So I am also thinking iron. I was considering getting a few 'root tabs' and burying one near the sword, but I haven't read the ingredients list for it. Does it even have iron. I have a large healthy colony of cherry red shrimp in this tank, as well as MTS. As well as fish fry. I don't think water-column metal (zinc) is my issue.  I have heard about people setting up a tank with washers under soil, but this seems like a bad idea to me. 

Has anyone added iron pills (USP grade made for people) under the soil?

How else could I add iron under the substrate without releasing too much in the water (killing my sensitive inverts)?


----------



## colinsk (Dec 29, 2008)

I did not add iron to my El Natural tank but in my Optimium Aquarium tank I used laterite in the gravel. You would have to wash it a lot to get it clean enough to not cloud the water with iron for the first few days. It is cheap and available however.


----------



## mommyeireanne (Oct 24, 2007)

I have been reading about the Ferrous Gluconate form, here in the 'fertilizing' room. But no details, just a few people mentioning 'you can use...' I want to keep the tank natural, and not hurt my inverts. (And I really don't want to be tinkering with it all the time.) I put the A sword in a month after I set the tank. I bought a small sick plant 50% off and stuck it in where I took out a rock. About a week later I froze some dirt and slipped in there, because it was in a dirtless spot after I removed the rock. It grew like mad for a while. It's huge now, but having trouble. I feed a plenty twice a day. My RCS breed like vermin. 
I'm going to try the iron or the root tabs (if they contain iron) unless someone gives me a compelling reason not to. I know too much iron can be poison, and I experienced lots of BGA in my 10g with Eco complete (though there was more wood matter in that soil, too. Subsequent soil was picked through better.). I'd love some help on this.


----------



## dwalstad (Apr 14, 2006)

mommyeireanne said:


> I too have lost my duckweed. I have had a UV filter for 15 months, had it in the old 20g. I grew duckweed there and in the 10g sans UV. I cannibalized both tanks to set up the new 75g in Oct '08. The duckweed grew for about a month and stopped.
> 
> 
> > Folks, I don't know what the answer is. Poor duckweed growth could be due to allelopathy, zinc, iron, lighting, ammonia, etc.
> ...


----------



## mommyeireanne (Oct 24, 2007)

Not really happy with my 'solution' but I stuck two root tabs (fertilizer) all the way down under the dirt, on the glass. They say 5% iron. Had a low Nitrate read (20 or less). Usually have zero Nitrate, Nitrite and Ammonia. All the shrimp, fish, snails and fry seem fine. I'm not so worried about growing duckweed (It's gone), but I'd like my Amazon Sword to be healthy. I waited a long time to have a tank big enough for it.


----------



## barthed (Sep 26, 2008)

I thought this would be the good thread to ask this question:

I've had no problem with duckweed for the last ~8 months or so in my NPT, but recently, it started to become white. My other plants are doing fine though. Could it be iron deficiency? How does your duckweed "decay" in your NPT?


----------



## dwalstad (Apr 14, 2006)

barthed said:


> I've had no problem with duckweed for the last ~8 months or so in my NPT, but recently, it started to become white.
> 
> Thanks for pics. They depict what I have seen (over the years) in my own tanks. Duckweed, Frogbit just wasting away.
> 
> When I retire (folks, it can't be too soon), I hope to work on this problem.


----------



## newbie314 (Mar 2, 2007)

The duckweed in my first El natural (2.5 gallon betta) lost it's duckweed and I reintroduced it, and it's barely hanging on.
Interesting though the val sp. was up an down in growth. I found using algea wafers from Hikari, seem to add some extra nuturients to the small tank and the val took off. Also Ricca seems to be doing well?

As for the 20g long, it's doing fine for duckweed, but I did move some val. sp into the 20g long, and I believe duckweed has slowed, and my hair/java moss seems to be deattaching from the rocks and floor and I'm noticing more snail shells that are being consumed. By the way I have no filters or circulation so there is no carbon pulling nutrients out. Definately overfeed the tank.

So I'm wondering if the vals. are pulling nutrients out, probably CO3? Anything else that might be the culprit.


----------



## dwalstad (Apr 14, 2006)

newbie314 said:


> I'm wondering if the vals. are pulling nutrients out, probably CO3? Anything else that might be the culprit.


Duckweed should be able to get most (if not all) of its carbon from the air (see 'Aerial Advantage' chapter in my book). Thus, duckweed is not really in competition with Val for either CO2 or bicarbonates.


----------



## totziens (Jun 28, 2008)

Funny to see so many people complaining about failing to keep duckweed and I was fighting to get rid of them. They grew like weeds in my tanks till I had to slowly remove them all with a lot of patience involved (it's the exact problem I had with Riccia). Maybe the room temperature of my country is suitable for them. I can see that a lot of Malaysians have the fear of duckweeds entering their tanks due to the high speed of growth and blocking away the light.  

Anyway, I am re-introducing duckweed by accident into my experimental tank now and I have no intention to remove them till they start blocking the light. Let's see how it goes. Maybe I should start exporting duckweed to all of you when they grow like crazy


----------



## colinsk (Dec 29, 2008)

I have duckweed growing in one of my tanks. (No Soil.) It is a volunteer. I was noticing that duckweed is a high protein plant. My guess it needs nitrates to grow well and the lake of nitrates in a El Natural aquarium could be the reason people have trouble.


----------

