[dwalstad]

Oxygen in the overlying water makes iron unavailable to plants. After the iron enters the water column it is converted to iron oxides, which plants cannot use.

You write: "Water lettuce are showing chlorosis, and their roots are growing desperately out of control."

I think your water lettuce looks just fine, sort of like mine in some tanks. If those roots can reach the substrate, then you will see real growth. If your other floater continue to grow, I would just relax.

I resisted iron fertilization for decades, because I wanted to stick with a purist approach. But I've given in. Once in awhile if I see real iron deficiency and my floating plants are dying, I'll add FeEDTA.
However, since (2021) I started keeping tanks without filters or aerators. Now, I have almost no problem with iron deficiency in my floating plants. [Filter bacteria and aeration (oxygen!) will remove soluble iron from the water column.]

These filter-less tanks are great. I now have 9 guppy breeding tanks with only floating plants and potted plants--no deep substrate. I've described them in a recent article 'Potted Plants for Fish Breeding Tanks' on my book's website: Planted Aquariums

 

[erose]

Oxygen in the overlying water makes iron unavailable to plants. After the iron enters the water column it is converted to iron oxides, which plants cannot use.

Does this always occur? If so, how do floating plants get iron at all?

I resisted iron fertilization for decades, because I wanted to stick with a purist approach. But I've given in. Once in awhile if I see real iron deficiency and my floating plants are dying, I'll add FeEDTA.

What would "real iron deficiency" look like? I thought the visibly darker veins compared to the rest of the tissue on the water lettuce leaves looked like chlorosis. The plants did not look like that when I got them; their leaves were uniform in color and the veins were not visible.

However, since (2021) I started keeping tanks without filters or aerators. Now, I have almost no problem with iron deficiency in my floating plants. [Filter bacteria and aeration (oxygen!) will remove soluble iron from the water column.]

These filter-less tanks are great. I now have 9 guppy breeding tanks with only floating plants and potted plants--no deep substrate. I've described them in a recent article 'Potted Plants for Fish Breeding Tanks' on my book's website: Planted Aquariums

In those tanks, do you just rely on livestock movement to bring water to the plants for nutrient exchange? I have a very lightly stocked tank, so I've been stirring around the water when I add my "magic potion" a few times a day to help with that. I know that terrestrial plants can deplete the water directly around their roots of nutrients, and that's why mycorrhizal associations are so beneficial. I imagined that the same thing could happen in stagnant water, since your book mentions that medium flow is beneficial for plants.

 

[dwalstad]

My tanks all contain well-fed shrimp, snails, and fish. All moving around and excreting. Tank is filled with plant nutrients!

In nutrient-depleted habitats, water movement can be vital for bringing scarce nutrients to plants. As nutrient levels increase, one would expect that water movement becomes less important.

When I got rid of the pumps, filters, bubblers etc from my tanks last year, I wasn't sure that my new system would work for my guppy breeding and rearing tanks. But it did, even better than I predicted! No nitrate build-up and ammonia/nitrite is zero.

I think you just have to devise a system that works for your tank(s). Stirring the water when you add nutrients is a good idea.

There may be mycorrhizal fungi associated with the roots of floating plants, just as some have been found on a few substrate-rooted aquatic plants. Good point.

 

[jatcar95]

What would "real iron deficiency" look like?

For my salvinia it mostly looked like stunted growth. I can tell how well they're doing based on their growth speed and root development. When they lacked iron it didn't look like the deficiency charts online, they just didn't grow. The roots looked a bit gnarled and the leaves stayed very small. When I started dosing iron the roots really started shooting out and the leaves got at least 3x bigger.

I suppose it's not exactly a "purist", but then, I suppose that was discounted when I started adding wonder shells for water hardness and dechlorinator to condition the tap water. It's not like I'm on a regimen exactly - I just throw some iron in when the floaters slow down and stop when they look good.

When I got rid of the pumps, filters, bubblers etc from my tanks last year, I wasn't sure that my new system would work for my guppy breeding and rearing tanks. But it did, even better than I predicted!

On my newest tank I am using a bubbler to keep the oxygen levels up. I have a lot of fish and plants in there and I worry they will start suffocating at night without it. Did you have any issues with this when you removed the aeration?

 

[erose]

Of course as I am about to begin my summer classes out of town, strange happenings occur. For the next two months, I'll be spending my week days in another city and only coming back here on the weekends. My roommate will keep an eye on the tank while I'm away.

So, 4 week update...

Stems were getting tall and floaters were blocking light, so I decided to give the tank its first trim on 6/14. Here's a before and after. Nothing drastic, just trimmed and replanted to promote thicker growth of the stems and thinned out the floaters to allow more light. Note that the left was taken on 6/14 and the right was taken the next day.

​

Since the trim, the tank has become very cloudy, so much so that looking through it long ways, I cannot see my hand on the other side until it is touching the glass. You can already see that it was cloudier just a day after the trim, but here is a photo taken today:

Not sure who the culprit of the cloudiness is between bacteria and algae. There is always a thick layer of biofilm on the surface when the tank is left undisturbed for any length of time. Additionally, the water doesn't look particularly green to me, mostly just white cloudiness, so I'm leaning towards bacteria. I will attach a comparison of tap water (left) vs. tank water (right) in test tubes so you can see the difference.

There are several variables at play. I have been feeding the tank either once or twice a day since 6/6. Because of the water lettuce, I also decided to dose Flourish Iron (which I realize is not chelated, but my friend had a bottle so I wanted to try it). I added 1mL twice, on 6/15 and 6/16. I also removed about half the floating plants and trimmed the water lettuce roots. All of these factors have probably resulted in a higher concentration of nutrients in the water column than there was before the trim, possibly contributing to the cloudiness.

Besides aesthetics, I don't think the cloudiness is necessarily harmful. Water parameters are all normal except for a pH rise from 7.4 to 8.0 between 6/14 and 6/18. GH and KH also reduced by 1 over the same time period. Maybe the cloudiness is actually algae, using CO2 and nutrients during photosynthesis and thereby increasing pH and decreasing hardness.

To my excitement, I have noticed a blooming community of tiny animals! I see ostracods hanging out near the surface and around the roots of floaters. Copepods skip their way across the glass, and I have seen several carrying eggs. Small white worms wiggle in the water column, and larger ones (1/4-1/2 inch in length) occasionally emerge from the substrate when disturbed. I am happy to see these critters playing their part in the ecosystem. I wonder if they like to eat whatever is clouding up the water.

My larger critters are doing well, too. I have seen numerous shrimp molts over the past week. The more sociable ones enjoyed sharing some boiled peas and cucumber. The largest ladies are saddled, so I hope to see shrimplets in my future. The many spotted ramshorns are growing, the biggest almost dime sized in shell diameter. They are funny, they shoot up like rockets to the surface sometimes for fast travel. My nerites are very shy, but they are coming out of their shells at their own pace (a snail's pace, if you will...)

All this is to say, maybe my leaving town is actually perfect timing. I go tomorrow morning, and won't be back until Thursday afternoon at the earliest. So until then, the tank will be left to its own devices and we'll see how it is when I get back. Probably better than trying to intervene myself. Just let nature take its course.

 

[johnwesley0]

My apologies. I must have missed it. What was the point of trimming the water lettuce roots? That's where all the nutrient uptake gets done. Also, I'm wondering if two hours is a sufficient siesta period?

 

[dwalstad]

Quote: "So until then, the tank will be left to its own devices and we'll see how it is when I get back. Probably better than trying to intervene myself. Just let nature take its course. "

Yes, let nature do the work!

The growth of algae causes a rise in pH due to CO2 uptake. Bacteria growth would lower it. Cloudiness is usually a mix of bacteria and planktonic algae.

Be careful with over-trimming. When you reduce the plant biomass too much, algae can gain an upper hand.

Those floaters with their big root systems have the "aerial advantage." They are highly effective in combatting algae and protecting your submerged plants.

 

[erose]

My apologies. I must have missed it. What was the point of trimming the water lettuce roots? That's where all the nutrient uptake gets done. Also, I'm wondering if two hours is a sufficient siesta period?

The root trim was purely aesthetic, they were blocking my view. Not the best reason, but they're already growing back so oh well.

2-4 hours for a siesta is something I've seen Diana mention frequently. On page 179 of the Ecology of the Planted Aquarium (we need a shorthand for that) the benefit of a siesta appears to increase linearly over the 4 hour period. A full 4 hours brings CO2 from 4 to 8 mg/L in Walstad's tanks, and the graph suggests that half that time would provide half that benefit.

The growth of algae causes a rise in pH due to CO2 uptake. Bacteria growth would lower it. Cloudiness is usually a mix of bacteria and planktonic algae.

I am giving a water sample to my friend who has access to a microscope in the lab he works in. I'll share here what he finds!

And yes, next time I'll do a more conservative trim. I didn't remove any stem biomass, but removing half the floaters and trimming the water lettuce roots seems to have really made a difference.

 

[johnwesley0]

2-4 hours for a siesta is something I've seen Diana mention frequently. On page 179 of the Ecology of the Planted Aquarium (we need a shorthand for that) the benefit of a siesta appears to increase linearly over the 4 hour period.

"Siestas help control algae, especially in tanks without CO2 injection."
page 179, EPA (Ecology of the Planted Aquarium)

 

[erose]

My friend was able to look at the water sample under the microscope today, but had a few limitations. The sample was pretty dilute, so it was hard to find things in it. And he was short on time. But he still sent me some interesting things!

I organized all the photos onto a presentation with my best guesses as to identification. Much harder than I expected it to be! I am inexperienced with identifying microscopic organisms, so take my opinions with that grain of salt.

The only thing I'm certain about is the presence of diatoms (specimen 2). The rest are very general and uncertain guesses.

Sometime later this summer (when we are both back in town) I will join him in the lab after hours to take a look for myself. That way I can spend as much time as I want looking at the microorganisms and taking pictures. What fun!

Anyways, peruse the pdf at your leisure.

 

[dwalstad]

Yes, it does sound like fun! But definitely will need help of a biologist! What you've photographed are the big animals (protozoa and probably debris--unless it's moving).
Your tank's cloudiness could be due to bacteria and micro-algae that you will not see without 400- 1,000X magnification. For the bacteria, you will need special staining or a dedicated microscope (phase-contrast?).
The size of bacteria range from 0.2 to 20 microns. Micro-algae are somewhat larger.

 

[erose]

Yes, it does sound like fun! But definitely will need help of a biologist! What you've photographed are the big animals (protozoa and probably debris--unless it's moving).
Your tank's cloudiness could be due to bacteria and micro-algae that you will not see without 400- 1,000X magnification. For the bacteria, you will need special staining or a dedicated microscope (phase-contrast?).
The size of bacteria range from 0.2 to 20 microns. Micro-algae are somewhat larger.

I will have to see if I can get access to one somehow. Maybe one of the labs I volunteer in has a beefier microscope.

My friend used a complex fluorescence microscope to get those photos. His lab works with fungal genetics, so he uses it to determine the presence of genes he's tagged. It's great for that purpose, but somewhat lacking for my interests.

Still interesting to see the larger animals, but I wish I could see more.

 

[erose]

5 week update...

Well, I left the tank alone for a week. The cloudiness hasn't changed much, but just about everything else has!

6/24/22
​

From the photo, the cloudiness looks better than it did last week, but the visibility longways is still poor. I would say it's maybe slightly better than last week. Hard to tell.

The pH normalized as well, back to around 7.6 where it's been for all of June.

The plants are really starting to look denser now which I love. The pearlweed is getting especially wild. It has sent out two runners over the carpet, challenging the hairgrass. The hairgrass is thick and holding the front lines against the pearlweed, but some has retreated towards the left side under the ludwigia.

As you can see, the water lettuce was not to be disgraced by my trimming of its roots. It has grown them back twice as long as before. I am giving up for now and allowing it.

The lily is exploding as usual. It is sending up two leaves today. One is sitting at the surface unopened. I've read mixed things about whether or not this plant forms lily pads like other species do. I've been hoping that it will.

In my time away, many of the plants have become greener. The salvinia finally looks normal again, and the water lettuce has improved some. The bacopa and rotala look much better as well.

The only plant struggling right now is the limnophila. It is responsible for the thin area in the center back. It is branching out laterally since the trimming, but the leaves are small, curled, light in color, and some are dying off. Interestingly, this was the plant that was growing the fastest in the beginning. Maybe it is an inferior competitor. I am interested to see what happens to it as time goes on.

As for the animals, there are exciting developments! I think I was right about the ostracods and copepods feeding off of whatever is in the cloudy water, because their populations have boomed compared to last week. I estimate that I'm seeing 2-4 times as many today than I was on the 18th. I saw at least ten copepods carrying eggs. Also, I think I have two species of ostracods present. Some are larger and transparent yellow while others are smaller and black, about the size and color of a poppy seed. Interestingly, there has been a sharp decline in the amount of detritus worms in the water. I did see large ones in the substrate, so maybe they grew big and decided to burrow. Unsure about that.

And the biggest news of the day... I'm going to be a grandparent! I was elated to see that my largest yellow shrimp is carrying eggs. It's a good sign. The shrimp are settled in, happy and healthy.

Things are going well. The cloudy water is not a catastrophe. The plants are growing, the crustaceans are breeding, and that's about all I could hope for.

 

[johnwesley0]

I had a brief experience with ostracods and copepods last year at about this same time of the year when I brought home some topsoil from a farm in North Carolina. I was convinced the creatures were daphnia at first until dissuaded from that view by the Au Naturel community. The soil was likewise accompanied by a grayish cloud when added to water. So, i'm wondering if this is also the case with your substrate which is a commercially sold "raised bed" soil mixture. They sometimes contain compost which can be pretty rich in bacteria. I would suggest letting the critters do their thing; they already seem to be making a difference. I wouldn't add any fish until the creatures are done procreating and have disappeared on their own.

 

[dwalstad]

Fun tank! Lot to enjoy watching.

 

[erose]

I had a brief experience with ostracods and copepods last year at about this same time of the year when I brought home some topsoil from a farm in North Carolina. I was convinced the creatures were daphnia at first until dissuaded from that view by the Au Naturel community. The soil was likewise accompanied by a grayish cloud when added to water. So, i'm wondering if this is also the case with your substrate which is a commercially sold "raised bed" soil mixture. They sometimes contain compost which can be pretty rich in bacteria. I would suggest letting the critters do their thing; they already seem to be making a difference. I wouldn't add any fish until the creatures are done procreating and have disappeared on their own.

Thanks for sharing your experience! I am using a raised bed soil, Bonnie's Harvest is the brand. Perhaps there is a similar thing going on in my tank.

I definitely don't mind the critters. In fact, I enjoy their presence, I wouldn't try to remove them. And I don't plan on adding any fish until my summer classes are over anyway so I can actually spend time around them.

Gives me plenty of time to consider what fish to get. At first, I was planning on a Betta, but they're kind of a dice roll when it comes to compatibility with shrimp. Lately I've been thinking about celestial pearl danios. My tank is the minimum recommended size for them though, so I'm not sure if they'd be comfortable.

 

[erose]

6 week update...

7/1/22​

I'll keep it brief this time. Tank is looking nice and jungle-y and I'm very happy with it.

Cloudiness is all but gone. Ostracods and copepods exploded even more than last time, can't look at a spot without seeing them. I think they might start to decline now that the tank is looking so clean. Photos of some of them attached..

I think the lily's preparing to make plantlets, several stems are forming a bud just before the leaf (photo attached). Floaters are looking healthy, much greener and less chlorotic. Ludwigia in the back had breached the surface before I topped off the water. Tiny crypt is putting out more leaves, but you can still barely see it in the tank shot.

Shrimp mama still has her eggs. No new pregnant ladies yet. And amanos are getting bigger. They're all so cute, so I'll attach some photos of them as well. And one of my pretty nerite.

I think I'll need to give it a trim tomorrow because I won't be able to visit next weekend. I will not remove any floaters, just trim and replant stems.

That's all for now. Hope you all had a nice week!

 

[erose]

Taiwan lily does appear to make lily pads. They are more arrow-like and less wavy than the submerged leaves. And I have another mama-to-be! Very sad I won't be back for two weeks.

 

[johnwesley0]

Yes, it's not always easy to tell what is going to happen when a lily sends out a "runner". It can be a pad or just another submersed leaf. How would you describe the growth beneath the substrate? Is it a bulb, a rhizome or just a root ball?

 

[erose]

Yes, it's not always easy to tell what is going to happen when a lily sends out a "runner". It can be a pad or just another submersed leaf. How would you describe the growth beneath the substrate? Is it a bulb, a rhizome or just a root ball?

I'm not sure about the growth under the substrate, I haven't poked around. Six weeks ago when I planted it, it was just a plantlet with a few roots. Do you have any idea how long it takes for a lily to grow a bulb?