# Brown Sludge in 4 ft Walstad tank



## Brendon (Aug 8, 2015)

Hey guys,

Although this is my first post, I have been reading the forum for a long time now. I set up a planted tank about 6 months ago now, using the Walstad method. When I was setting it up I read a lot of the topics, particularly the sticky soil thread. It was heavily planted (crypts, val, java ferns, banana lillies etc) from the start, driftwood, has a powerhead for circulation, no oxygen and has a T8 lighting on for a total of 10 hours a day with a 2 hour break in the middle. (I have tried 8 and 12 hour days).

I found a organic soil and mineralised very well, and used your average sand as the cap. It wasn't pool sand. This is where I think I went wrong but need your advice. I sieved all the fine particles out leaving approx 2mm granules. I then rinsed it multiple times and set up the tank, making sure to cycle it.

I also have natural slate as the background in the tank. I selected the slate without any rust marks and thoroughly rinsed it before putting it in.

I did lose a few fish through the first month or so but haven't lost any for ages. They don't gulp at the surface, so oxygen appears fine. The plants are all looking healthy and growing very well.

The problem is my tank gets overrun with brown sludge. (See attached pictures) There has always been a little bit of it but now it is getting out of hand. I have to do water changes nearly every week and within a week the sludge is back. It clogs up the powerhead, makes the water cloudy and covers the plants.

I have read that it might be the silica from the sand. I was going to change the sand but before I did that I just wanted to see if anyone else has had this problem and if they had any advice on what should I do?

*Tank:* 4 ft, 10 danios, 3 dwalf gouramis, 2 bn, 2 silver sharks, 4 rummy nose, 1 tetra.
*Water parameters:*
Temp: 23.0 Celsius 
PH: 7.6
GH: 5
KH: 4
Ammonia: Between 0 & 0.25ppm
Nitrite: 0
Nitrate: Between 0-0.25ppm


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## Patriot100% (Nov 12, 2011)

It could be diatoms from the silica that'd comes from the sand.


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## BruceF (Aug 5, 2011)

That looks like dirt to me but it is hard to tell. Is the water cloudy or is that the pictures. Can you remove it from the plants simply by shaking them or brushing them off? I mean is it stuck to the leaves or not?


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## Brendon (Aug 8, 2015)

BruceF said:


> That looks like dirt to me but it is hard to tell. Is the water cloudy or is that the pictures. Can you remove it from the plants simply by shaking them or brushing them off? I mean is it stuck to the leaves or not?


Hey Bruce, yes the water is very cloudy. After a water change and clean out of the filter, I just have the basic filter media, the water settles and goes clear. And then it slowly gets cloudy again. Brushing it does remove it from the plants.


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## BruceF (Aug 5, 2011)

Assuming you aren't having major problems with fish and plants I would suggest you vacuum this stuff thoroughly and do a water change twice a week until it stops. The fact that the water gets cloudy suggests you have a bacteria problem of some kind. Most likely the tank is still cycling and it isn't stable. 

Do you have a filter besides the power head? Are you cleaning the filter media with the water from the tank? Treating the water with prime or some such chemical?


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## Brendon (Aug 8, 2015)

Thanks for the replies Bruce. Would the tank still be cycling after 6 months? 

Nope, no other filter than the powerhead. The only chemicals I have used in the tank have been api stress coat with the water changes and stability when setting up and for the first few months with water changes. 

I am thinking it could be very fine dirt, and might just be seeping through the cap around the plants and with the occasional gas bubble.


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## BruceF (Aug 5, 2011)

Yes the ammonia readings suggest you haven't got the cycle under control. Most likely the substrate is causing the problem. You could try using one of the water treatments that treats for ammonia like prime does. You probably should be adding one anyway, Have you tested the tap water?


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## f1ea (Jul 7, 2009)

Pay attention to your fish and see if any of them disturb the substrate. Maybe the silver sharks?

Also, you don't have enough plants. And from your list, seems like no stem plants. These are absolutely crucial at the beginning of soil tanks.

Light.
A T8 on a 4ft tank? How many watts, how many bulbs, how tall is the tank, how high are the lights, how old are the bulbs?

Check for trumpet snails. Wait for your lights to go off... wait a couple hrs, then suddenly turn the lights on. See if there's any snails hanging around.

I think mineralizing soil is overrated... I'd rather leave the soil as-is for a true Walstad-style tank. If you have a lot of light, maybe it's better to mineralize. But i've gotten better results (with various amount of light) without mineralizing the soil. Just be careful not to make a soil mess on your initial setup.


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## hardcorehansolo (Nov 8, 2011)

Patriot100% said:


> It could be diatoms from the silica that'd comes from the sand.


I agree-

http://www.guitarfish.org/algae

brown algae/diatoms. Silica makes up a big part of diatoms, so that follows.


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## Crooks (Sep 26, 2015)

Hey!

In your second picture it looks like there is lots of gas collecting under the gravel (could be just water stains tho), that means that your soil is still decomposing (could be a high cellulose content or whatever, every soil is different). Now if bubbles keep rising they might also tow organic material and -more importantly- water rich in ammonia and CO2 with them, explaining the turbidity.

What I'm saying is: Walstad tanks are like a fine wine, do some water changes (as in remove the mulm) if it bothers you or the plants and wait a year.

Hope this helps a bit.
Crooks

Btw. I think you have hella fast growing plants in there, also some that reach the surface. Fine by me honestly.
Oh hey and also consider connecting, like, a huge canister filter to the tank. Then you won't have to do water changes just put your hand in the tank and wiggle a bit to remove dirt. It's not good but less work. Sell it when your soil settles.


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