# Brown fuzz on sand in new Walstad tank



## Endlesserror (Sep 28, 2020)

I've been keeping fish in various capacity for 3 years. This summer, I discovered Diana Walstad's Ecology of the Planted Aquarium and found it fascinating and informative and wanted to give this a shot in part because I am an avid gardener and the reason I got into keeping fish was to keep aquatic plants. I loved Walstad's book because it basically diagnosed all the different types of problems I've had with aquatic plants in any setting that is not an outdoor patio pond.

So I decided to set up my indoor 10 gallon tank using this method. I used garden soil which I submerged starting Aug 1 before adding to my tank and then on September 13th I added the soil and planted out my tank trying to follow the directions in the book as closely as possible. I went with the garden spoil because this is what I used to grow water lilies and lotuses in my patio ponds and have had great success with it. Within days I started noticing a light brown sort of fuzzy material on top of my substrate.

Lurking on this forum I realized that I definitely did not have enough rooted plants and wondered if that was the problem. So then on September 24th I increase the number of plants significantly and siphoned out the fuzz as best as I could. But again within a couple days of adding the new plants I started noticing the same light brown fuzz. I wondered at first if it was mulm accumulating on top of the sand which I know is not a recommended substrate for a low tech tank because it can be too fine and prevent the mulm from sinking back into the soil layer. I tried to do my best keeping the sand layer less than .5 inches throughout. I don't think it's mulm because before trying the Walstad Method with this same sand s I wasn't seeing this material accumulating on top of the sand. It seems concentrated in one area in front of the Apontogen bulb in the center of the tank and in almost an entirely straight line. 

When I tested the water parameters this morning pH is 7.5, ammonia, nitrates and nitrites all at 0. Some crypt melt I think going on in the newest batch of plants I put in but otherwise the plants seem to be doing okay.

Any ideas on what I'm doing wrong /what the brown stuff is? I don't think it's soil because it's so much lighter in color than the soil sublayer itself. I wondered if it was brown algae but everything I read online seemed to indicate that happened due to high nitrates or dissolved organic carbons. 

Would appreciateany suggestions on what to do...right now I'm wondering if I need to break this down, pull out the sand and replace with gravel which ugh so much work!

Including three picture.

1. Initial tank setup from 2 weeks ago with not enough rooted plants.

2. After adding more plants 4 days ago.

3. Close-ups of light brown material.


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## dwalstad (Apr 14, 2006)

I wouldn't worry about a little fuzz on the substrate. And I would not even consider tearing this nice tank down.

In comparing the pictures, I noticed that you removed a lot of the Hornwort. That may have stimulated the problematic "carpet"--probably a little ecosystem of algae/fungi/bacteria. 

I would vacuum or spoon out the carpet and let the Hornwort grow for awhile. Your tank could use the extra plant biomass. Sometimes over-pruning plants can give algae the edge. It takes a little experience to learn how to strike a balance.


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## Endlesserror (Sep 28, 2020)

Thank you for responding! I put all the hornwort back (wasn't sure if it would shade out the crypts below too much) and siphoned up the brown stuff.

Will keep monitoring and keep my fingers crossed. I've killed so many aquatic plants indoors, I really hope this is my turning point!


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## hoppycalif (Apr 7, 2005)

Are those two "rocks" on top of the substrate, or sitting on the glass, with substrate around them? If they are sitting on top of the substrate you will soon have some stinking black stuff under them. I know you didn't ask about this, but I have made that mistake enough times to always look for it.


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## Endlesserror (Sep 28, 2020)

Yes, those are lava rocks sitting on top of the substrate. Sounds like I should embed them into the soil layer and directly on the glass? I was hoping the plant roots from nearby would eventually spread to grow under them.


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## hoppycalif (Apr 7, 2005)

When you put something bigger than about a half inch in diameter on top of the substrate it makes the substrate under it be anaerobic - minus oxygen in the water. That leads to hydrogen sulfide formation, and that really stinks, plus being very toxic for the plant roots. It is sort of like trying Russian roulette and forgetting to remove the bullets first. I would just recite a few minutes of foul language, then start over.


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## t2000kw (Jul 29, 2006)

hoppycalif said:


> When you put something bigger than about a half inch in diameter on top of the substrate it makes the substrate under it be anaerobic - minus oxygen in the water. That leads to hydrogen sulfide formation, and that really stinks, plus being very toxic for the plant roots. It is sort of like trying Russian roulette and forgetting to remove the bullets first. I would just recite a few minutes of foul language, then start over.


Would the original poster just be able to bury the rocks to near the bottom of the substrate?


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## Endlesserror (Sep 28, 2020)

I was hoping because lava rock is so porous it wouldn't lead to making the soil underneath anaerobic. I will periodically poke down there with a butter knife and see I guess. 


I am reluctant to pull them out because I've glued anubais on both rocks and the plants are well established and healthy. In fact they're the only plants I've managed to keep alive in my tanks for the past couple years when following the traditional sand only substrate with weekly large water changes.


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## hoppycalif (Apr 7, 2005)

Could you attach legs to the wood pieces, so they support the weight of the wood, but don't put any pressure on the thin substrate between the wood and the substrate? I haven't tried this, but I think it would work.


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## dwalstad (Apr 14, 2006)

If it were my tank, I would just push those lava rocks to the bottom so that they rest on the glass. Sixty seconds...

I wouldn't tear down the tank when this can be so easily fixed.


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## Endlesserror (Sep 28, 2020)

An update: I pushed down the rocks as recommended. The fuzz has not reappeared. Thanks for the advice on this!

I am a little worried that my tank is still going through its usual nitrogen cycling process. Maybe I misunderstood this from Ecology of the Planted Aquarium but I thought that with this style of low tech tank we are trying to avoid a build up of nitrates because plants prefer ammonium.

Results from this week's tests:

PH 7.5
Ammonia 0
Nitrites 0
Nitrates 5ppm
KH 4
GH 8

Last week, nitrates were at 0. The initial crazy plant growth has also slowed down. 

Does this mean the denitrification process isn't happening the way it should? Anything in particular I should be doing?


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## dwalstad (Apr 14, 2006)

I wouldn't worry about nitrates unless they reach 30-60 ppm. Plants ignore them as they take up the preferred ammonia.

The main thing to monitor is plant growth and fish behavior. All else is interesting but incidental.


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## Endlesserror (Sep 28, 2020)

Thank for all your advice on my tank, Ms. Walstad and hoppycalif! 

Here is a three week update: water parameters are the same. I did a couple of 20% water changes while trying to siphon up the constantly shedding hornwort needles. I have a serious pest snail problem and they just go mad over the hornwort. 

I also impulse purchased some red cherry shrimp from a local hobbyist (first time keeping them!) I thought I'd hate them because I'm not a huge fan of bugs but am finding them really fun to watch. They've also been a huge help with the hornwort needles which at their absolute worst were carpeting the entire tank.

Do I need to be more aggressive about getting the dead hornwort needles siphoned up or is it ok to rely more on the shrimp?

I had a yellow leaf or two intially and was chalking it up to plant trauma from initial setup but as a few more leaves continued to discolor, I decided to move forward with adding KCl from salt subsitute about a week ago. Since then I haven't seen any addition yellowing.

Lots of growth on the Apontogen and water sprite. Each of the anubais also got a new leaf and the crypts seem to have stabilized.


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## dwalstad (Apr 14, 2006)

What a pretty tank! 

Glad you have developed a liking for "bugs." 

I've enjoyed having RCS (and Blue Dream Shrimp) in my guppy tanks. They help clean up messes and algae. A little like snails--unappreciated at first but they become an additional source of "tank entertainment."


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