# Questions about the Walstad Tank Method



## TheBettaAquarist (Jun 11, 2021)

I have become so fascinating with walstad tanks as of lately. I want to set one up in the near future, and all though this wont be for another month or two I have some questions.

Its my understanding that you do 1" - 1.5" layer of soil and then you cap that off with another inch of gravel/ sand, is this correct? Is there anything in some soils that I should avoid? or will any soil do?

I also understand that because its heavily planted the nitrogen cycle is not necessary. I can add the fish the same day I add the plants? But I also heard that you should wait two months before adding the fish to let the aquarium balance out. Whats your opinion on this?

And of course in walstad tanks because theres no filtration, Diana reccemends to have some flow in your aquarium. This would probably help with preventing the bio film that lives on the surface of the water when theres no flow. But then also if something were to go wrong with your plants you have that added source of oxygen. Is this right?

I have read that after a few years the substrate will become "exsahusted" so I will have to supplement the plants some way. Can this be done through root tabs?

Anything else I should know?


Its going to be a 5 gallon that will probably house some pumpkin shrimp.
I'm also considering ordering the book off amazon because my local library doesn't have it.
Thanks guys!


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## maico996 (Nov 6, 2016)

I'm sure others will chime in but here's my two cents...
Find a soil that has the least amount of additives like additional fertilizers, nitrogen, etc. The soil I used is Miracle-Gro Raised Bed Soil. According to the label it’s made up of peat, processed forest products and/or compost, poultry litter, alfalfa meal, bone meal, kelp meal and earthworm castings. Total nitrogen is 0.09%
• 0.008% ammoniacal nitrogen
• 0.028% other water soluble nitrogen
• 0.054% water insoluble nitrogen (from poultry litter, alfalfa meal and kelp meal)
Available phosphate is 0.08%
Soluble potash is 0.09%
Calcium is 0.02%
You shouldn't need to add anything to it unless you have soft water, in which case you can add some crushed oyster shell to help raise the hardness. I added a thin layer between the soil and gravel.
Stick with one inch of soil and one inch of gravel or sand.
Some will say to mineralize the soil first (rinse and dry a few times) but I didn't with no adverse effects. I did add a little clay cat litter to my soil which was a mistake......so don't do that. 
I added my fish and shrimp the same day I started the tank and everyone is alive and happy. Just make sure you plant heavily because you'll probably have some die off as the plants sort themselves out. Once again, plant heavily! 
I have a power head at one end of my tank which provides some gentle flow. You'll probably have some bio film at first which is normal. You can soak if off the surface with a paper towel. Eventually it will go away.
If you overfeed your fish, as Diana suggests, the excess fish food along with fish poop will provide a nutrient supply to the soil which your plants will take up.
You may have to poke the substrate several times to get oxygenated water into the soil to prevent an anaerobic condition which can become detrimental to good plant growth. Lots of rooted plants (not stem plants) will help keep your soil oxygenated. Floating plants (water lettuce, hornwort) will help when your tank first starts and once things settle in you can decide if you want to keep them or not.
Get Diana's book and read it before you start. It has an immense amount of information in it that will help your first tank succeed, as will this forum.
Have patience! If you start off on the right foot, ask questions here and let the plants do their thing, you'll likely have a successful tank.

Good luck!


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## TheBettaAquarist (Jun 11, 2021)

maico996 said:


> I'm sure others will chime in but here's my two cents...
> Find a soil that has the least amount of additives like additional fertilizers, nitrogen, etc. The soil I used is Miracle-Gro Raised Bed Soil. According to the label it’s made up of peat, processed forest products and/or compost, poultry litter, alfalfa meal, bone meal, kelp meal and earthworm castings. Total nitrogen is 0.09%
> • 0.008% ammoniacal nitrogen
> • 0.028% other water soluble nitrogen
> ...


Awesome! Thanks!
Just bought the book too!
some people are saying the soil will only last for 2ish years before I should start adding nutrients, whats your experiance with that?

Here are the plants I will want to include, let me know what you think:
do you think that crypts and some dwarf sagiteria would be fine? 
thanks!


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## johnwesley0 (Feb 23, 2021)

TheBettaAquarist said:


> Awesome! Thanks!
> Just bought the book too!
> some people are saying the soil will only last for 2ish years before I should start adding nutrients, whats your experiance with that?


Don't overlook the amount of livestock poop that builds up over time. Some hobbyists call it, _mulm. _It works its way into the substrate and is supposedly rich in Iron and other nutrients. And, even after your original dirt has lost its potency it can still have high CEC value as a binding agent between your plant's roots and soluble nutrients, like ammonia, that are in the water column.


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## dwalstad (Apr 14, 2006)

Small Crypts and dwarf Sag are perfect. Crypt wendtii (bronze variety) is a beautiful plant and good grower.


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## florida phish fan (Dec 3, 2020)

Question please? If the soil doesn't have any additives (as compared to, say, ADA Aquasoil) then how do the plants get nutrition?

Reason I ask is I've got a tank with depleted Aquasoil. Since I didn't vacume the substrate I thought the mulm would fertilize the plants. 

I wound up with a ton of mulm (and a LOT of poop) yet I still wound up with zero nitrates and the plants started showing deficiencies until I started adding ferts. 

I actually thought 0/0/0 was a good thing and wondered how often should I be doing water changes with zero Nitrate readings (something I still wonder about). 

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## johnwesley0 (Feb 23, 2021)

The reason you're showing 0 nitrates is because 1) either so much ammonia/ammonium is being absorbed by the plants that nothing is left over for beneficial bacteria to turn into nitrite and nitrate or 2) some combination of bacteria and flora are utilizing the nitrate. Either way it's a good thing and you can relax the water changes. I'm not sure what Aqua Soil is, but some soils retain a clay like ability to bind nutrients from fish and plant waste in a way that supports root absorption or _cation_ even after they've exhausted their original ingredients. But this is not universally true. If your plants are showing signs of nutrient depletion, by all means supplement their diet.


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## Michael (Jul 20, 2010)

ADA is famously vague about what Aquasoil actually is. But their method calls for fertilization right from the start, so we can assume that Aquasoil never contributes much fertility. It SEEMS to have high cation exchange capacity (CEC), so it should be able to absorb nutrients from the water and release them to plants later.

In a mature Walstad tank, most of the nutrients come from fish food. But it is possible that your plants are missing something, especially if your water is extremely soft.


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## dwalstad (Apr 14, 2006)

Your nitrates are zero? If you are doing a lot of water changes, you are removing nutrients the plants could use. Remember that there's a balance between the fishfood input of nutrients and their removal by tank cleaning. I would scale back on water changes. 

Hard to say what your plants are missing without more information. What is the hardness of water in your tank?


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## codnodder (Jun 6, 2017)

TheBettaAquarist said:


> I also understand that because its heavily planted the nitrogen cycle is not necessary. I can add the fish the same day I add the plants? But I also heard that you should wait two months before adding the fish to let the aquarium balance out. Whats your opinion on this?


If you read Diana's book you will find the timing for adding fish is largely dependent on the type and quantity of plants you start with. In my case, I don't really buy plants anymore, I'd rather take little cuttings from other tanks and let them get started. It's slower, but interesting in its own way. Without fish to worry about, a slow start tank will go through an interesting cycle of nutrient blooms, small crustaceans, and odd pond creatures. If the soil is "hot" (high nutrients), the water will probably go cloudy or green for a while. I know when the tank is "ready" when the water goes clear. Unsurprisingly, this occurs just about the same time the rooted plants have become established. So, either start with a large number of the right type of rooted plants (see Diana's text), or take your time and let your plants establish on their own.



TheBettaAquarist said:


> And of course in walstad tanks because theres no filtration, Diana reccemends to have some flow in your aquarium. This would probably help with preventing the bio film that lives on the surface of the water when theres no flow. But then also if something were to go wrong with your plants you have that added source of oxygen. Is this right?


I have slowly worked my way down to simple sponge filters. They do not trap crustaceans or fry, and they gently move the water. I think surface bio-film is primarily protein, although perhaps someone will correct me on that point. In any case, if you have the right balance of plants the surface will remain fairly clear. I find floating plants make a big difference. Water lettuce (pistia stratiotes) is one of the more maintainable varieties. Duckweed gets crazy.



TheBettaAquarist said:


> I have read that after a few years the substrate will become "exsahusted" so I will have to supplement the plants some way. Can this be done through root tabs?


I have had Walstad tanks that were in continuous operation for more than 10 years with no sign of substrate exhaustion. Overfeed, and keep snails.



TheBettaAquarist said:


> Anything else I should know?


Snails.

I have come to appreciate having a variety of snails in the tank. A naturally planted tank that is established for any period of time will have them eventually, so you might as well embrace it. I have breeding populations of bladder snails, common ramshorn, and malaysian trumpet snails. If you keep all three, they tend to balance each other out. I think snails are very important in a low-maintenance planted tank. They consume all extra food and process it down to the next level for bacteria.

There are multiple varieties of malaysian trumpet snails. The big ones are not very attractive to look at. I tried a few different sources until I found the small one (I think the smaller one is melanoides tuberculata).

Good luck.


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## florida phish fan (Dec 3, 2020)

dwalstad said:


> Your nitrates are zero? If you are doing a lot of water changes, you are removing nutrients the plants could use. Remember that there's a balance between the fishfood input of nutrients and their removal by tank cleaning. I would scale back on water changes.
> 
> Hard to say what your plants are missing without more information. What is the hardness of water in your tank?


Hi thanks for the reply I've read your book twice! 
It's what turned me into an accidental addict. 

Since I wasn't seeing nitrates I stopped water changes - just topping off. (in general, I let the tank get a little hairy so foraging fish have things to graze on all day). 

I'm out of the country but will provide more info + pics asap. There's a ton of plants, and a low livestock bioload so it seems like plants have been hungry for a while. 

Example Java Ferns are potassium hogs - didn't know that and started seeing pinholes, larger holes and general deterioration. 



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## johnwesley0 (Feb 23, 2021)

Well, now I have a question. My plants are doing relatively well; I'm especially taken with how my three month old water lily has sprouted huge, floppy leaves that seem to portend some kind of aerial ambitions. The thing is, I think it is all being fueled by an eruption of decomp in the lily's pot. My nitrates were off the charts (80ppm) before I did a 20% WC. A generous reading of the color chart might give it a 40ppm today along with a 0.25 ammonia reading. Should I do another WC or adopt a wait-and-see attitude?


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## ronnie (Feb 26, 2021)

To second, are zero nitrates a potentially bad thing?


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## dwalstad (Apr 14, 2006)

johnwesley0 said:


> Well, now I have a question. My plants are doing relatively well; I'm especially taken with how my three month old water lily has sprouted huge, floppy leaves that seem to portend some kind of aerial ambitions. The thing is, I think it is all being fueled by an eruption of decomp in the lily's pot. My nitrates were off the charts (80ppm) before I did a 20% WC. A generous reading of the color chart might give it a 40ppm today along with a 0.25 ammonia reading. Should I do another WC or adopt a wait-and-see attitude?


I would do another water change. It's hard to imagine that that high level of nitrates could come from just a little pot of soil, especially after you've added those umbrella plants.
Your plants don't seem to be growing enough to mop up the nitrates. 
What is your water hardness? If you have softwater, that could be what is holding back plant growth.


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## johnwesley0 (Feb 23, 2021)

dwalstad said:


> I would do another water change. It's hard to imagine that that high level of nitrates could come from just a little pot of soil, especially after you've added those umbrella plants.
> Your plants don't seem to be growing enough to mop up the nitrates.
> What is your water hardness? If you have softwater, that could be what is holding back plant growth.


It's a bit of a mystery. GH and KH hover around 4-5. I would have to guess the floaters were doing the lion's share of the mopping up; there's no question they are the fastest growing things in the bowl. I came very close to having -0- nitrates about a month ago. Then, i stopped scooping them out on a regular basis. I've grown to like the thick carpet effect they have when the water spangles start piling on top of one another (and, most especially with the umbrella papyrus emerging from among the pile.) But, I wonder whether that somehow comes at the expense of their efficiency?

P.S. I will give the wonder shells a whirl since they seem to be creating quite a bit of excitement and besides, I haven't made a major investment in nutrients in a blue moon (old potting soil, old plant tabs - an ancient shell rock.) It won't break me!


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## dwalstad (Apr 14, 2006)

Sounds good. Plants that have stopped growing become less efficient at removing nutrients. If they start dying, then they add nutrients to the water.


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