# Thoughts on the Walstad Method



## Reediculous_nanotank (Jan 12, 2019)

I thought it might be interesting to spark a discussion about thoughts and experiences with the Walstad method, and by this I mean the full method in Diana Walstad's book: moderate fish load, moderate feeding, no filter, no fertilizer, no CO2, no water changes (after the tank has been established), ~1'' dirt and compost substrate with a 1-2" gravel cap at 2-3mm grain size, and low light (probably CFL). There is also an emphasis on fast growing plants and/or aerial and floating plants, as well as strongly rooted plants. So not stem plants. I might have missed an important point, but from my experience on this forum the list above list seems to comprise the key points of the method. This list starts with some negatives, and then praises the method at the end, so please read it all the way so you don't start to think that I'm completely biased.

The first thought I have is about allelopathy. It seems to me that in the high-tech world allelopathy recieves very little attention, not that its existence isn't ever acknowledged, but it isn't given much importance. My thought it that perhaps with frequent water changes the allelopathic relationships between plants become much less relevant because of dilution. Of course, as Diana's book mentions, allelopathy also occurs in the substrate, but this is probably also mostly relevant in a dirted tank because the dirt layer doesn't get as much water circulation as in other types of substrates.

I have also thought about water changes in another regard. Because if you don't do water changes and only top up then your evaporation rate may require a level of water input that causes an accumulation of whatever is dissolved in it. I think unless your water is very clean it seems that top ups will usually cause some form of accumulation, probably of something that plants don't consume a lot of, like calcium. I have tried to figure this out in a way that water changes can still be avoided, but I haven't thought of one yet, other than finding an optimal mixture of RO/DI water and tap water that is balanced with your evaporation rate and the plants consumption of whatever is in the tap water. And it seems that this could also require a long period of water testing before it all gets balanced out. On the other hand, if you're not getting accumulation, you could be getting a deficiency if your top-up water is lacking calcium or another nutrient that isn't easily obtained through fish food.

It also seems that the Walstad method optimizes fish keeping rather than plant keeping. Not sure if that's a controversial opinion or not, but I'll explain why I think it. The idea behind the Walstad method is generally to put in a large amount of plant species and let things work themselves out, wherein some plants will die. Then you end up with a tank that has balanced itself, and it becomes very low maintenance if you can get away with no water changes, and fish poop being the only fertilizer required. This is where I think fish keeping becomes optimal; the inputs are fish food, light, and maybe a heater, which is very cost effective compared to running large filters to deal with the fish waste, instead creating a symbiosis between fish and plants. I think this cost savings is the main benefit of the method, as well as it being very low maintenance, with just water top ups, fish feedings, and occasionally trimming the plants. On the flip side, you can't exactly keep the plants you want to keep, because some might die off due to allelopathy, require CO2, require higher levels of some nutrients, require higher light, or maybe even higher flow. That's why I believe that the method is optimal for fish keeping, not plant keeping.

TLDR: in my opinion the Walstad method makes fish keeping really easy if water top-ups don't lead to accumulation of dissolved solids from tap water. Allelopathy may be separate but related issue. The method doesn't provide as much freedom as far a plant keeping, but it does make keeping the plants that do work very easy. It is inexpensive and generally low maintenance. 

Please share your own thoughts! I'm excited to see what others think.


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## Michael (Jul 20, 2010)

This could be a very interesting thread, thanks for starting it! Of my many thoughts and opinions, I'll start with just a few.

The Walstad method enables me to have beautiful planted aquariums with healthy fish, and does not require a huge budget or high maintenance. This is exactly what I want from the hobby. Yes, the method imposes some limitations. Plants that in nature are actually obligate emergent species sometimes do not thrive in Walstad tanks because of lower light levels and no access to atmospheric CO2. But that still leaves a huge variety of things to grow, and numerous aesthetic possibilities.

The mere presence of plants limits fish keeping, unless you regard plants as totally expendable. And the soil substrate further limits fish by ruling out digging and burrowing species. But I've managed to push that envelop pretty far in some cases.

After 10 years of Walstad tanks, I've tweaked the method a little. I keep more fish than is optimal for the method. So I have lots of circulation in my tanks, mostly from power filters with mechanical media only. And I do change the water once in a while. If I am being diligent, a partial change once a month. My water is hard, so this helps with concentration of minerals from evaporation, and the build up of dissolved organic compounds. If I am neglectful, there might be three or four months between water changes. But fish and plants remain healthy and attractive.

I enjoy my aquaria, and do not feel like a slave to them. If life gets busy and the tanks don't get all the maintenance I would like to give, no catastrophes occur. And with a water change and a trim, they bounce back almost immediately.


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## Reediculous_nanotank (Jan 12, 2019)

Thanks for your response Michael! I'm hoping to hear a lot of perspectives and have a discussion about the pros and cons of the method, so I really appreciate your response.



Michael said:


> The mere presence of plants limits fish keeping, unless you regard plants as totally expendable.


At first I couldn't think of a reason for this, but are you referring to fish species that will eat plants until they're gone, or uproot them endlessly due to their larger size?


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## hoppycalif (Apr 7, 2005)

I haven't yet tried the El Natural method, so my opinions are just opinions. I have enjoyed working on my high light to low light tanks over several years now, but adding several years to my age when I got serious about planted tanks means I'm not at all young now. So, i'm no longer physically able to do as much work on any aquarium. This makes the El Natural method a natural method for my age. My next housing move will be to a Senior Living facility, where I will have limited room for any hobby. That is when I make the switch to El Natural.

I also enjoy experimenting and trying to find some better ways to make decisions than just using the myths from the ages, like "watts per gallon" and "you need 30 ppm of CO2", etc. There are still some subjects that can be studied for improvements in the El Natural method, and I plan to play around with that too, using a 10 gallon tank, with a divider in the middle to make it a pair of 5 gallon tanks that can easily be set up with exactly the same parameters, opening the door to some side by side testing. (For example, use activated charcoal to remove any large molecule chemicals, like allelopathic chemicals released by plants in one of the tanks to see if there is an obvious effect of any kind.)

I'm looking forward to the future with El Natural!!


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## Michael (Jul 20, 2010)

Reediculous_nanotank said:


> At first I couldn't think of a reason for this, but are you referring to fish species that will eat plants until they're gone, or uproot them endlessly due to their larger size?


Yes. There are some beautiful Rift Lake cichlids that I would like to try. Some of them are herbivores, and some are relentless diggers. But I've been able to keep_ Lamprolgus ocellatus_ and _Judlidochromis reagani_ in Walstad tanks.


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## Reediculous_nanotank (Jan 12, 2019)

Michael said:


> Yes, the method imposes some limitations. Plants that in nature are actually obligate emergent species sometimes do not thrive in Walstad tanks because of lower light levels and no access to atmospheric CO2. But that still leaves a huge variety of things to grow, and numerous aesthetic possibilities.


This is also an interesting point. Do you have examples of obligate emerse plant species that are commonly used as submerse plants in aquaria?

Is a plant that lives in a riparian zone with periodic flooding but only flowers (and thus sexually reproduces) when emerse an obligate emerse species? Or are obligate emerse species simply plants that can't survive for long periods of submersion? Sorry, those seem like pretty heavy-duty questions, but I'm curious to see if anyone can clarify this point. As Michael has pointed out, due to low light and less CO2 in Walstad tanks it seems relevant to this thread.


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## Michael (Jul 20, 2010)

Obligate emergent plants are those that must be exposed to air at some point to complete growth and reproduction. Typically they never grow continuously submerged in nature. There are also facultative emergent plants that can survive some exposure to air, but do not require it. Of course there are species that are on the border

I think of _Lobelia cardinalis_ as an obligate emergent. _ Anubias_ is a facultative emergent--it can survive indefinitely either submerged or exposed to air (if the humidity is high enough). Some species of _Nymphaea_ are on the borderline. We can keep them submerged indefinitely, but they can't seem to flower until they have some emergent leaves.

CO2 supplementation changes all the rules.


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## Reediculous_nanotank (Jan 12, 2019)

Michael said:


> Obligate emergent plants are those that must be exposed to air at some point to complete growth and reproduction. Typically they never grow continuously submerged in nature. There are also facultative emergent plants that can survive some exposure to air, but do not require it. Of course there are species that are on the border
> 
> I think of _Lobelia cardinalis_ as an obligate emergent. _ Anubias_ is a facultative emergent--it can survive indefinitely either submerged or exposed to air (if the humidity is high enough). Some species of _Nymphaea_ are on the borderline. We can keep them submerged indefinitely, but they can't seem to flower until they have some emergent leaves.
> 
> CO2 supplementation changes all the rules.


Interesting, and thanks for the definition of obligate emersed plants!


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## mistergreen (Mar 3, 2007)

Anubias flower under water sometimes. Seems like they don't know if they're submerged or emersed.


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## Reediculous_nanotank (Jan 12, 2019)

mistergreen said:


> Anubias flower under water sometimes. Seems like they don't know if they're submerged or emersed.


Haha, true.

I'm still especially curious about people's thoughts on a possible relationship between allelopathy and the Walstad method (or any other "no water changes" method, I suppose). My original post elaborates more.


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## hoppycalif (Apr 7, 2005)

To the best of my knowledge, no one has ever demonstrated that allelopathy is a factor in planted aquariums. That is possibly because it is very difficult to do so. The chemicals involved are not easy to identify, and not easy to replicate. Diana Walstad believes that allelopathy between competitive plants is a significant factor in why some plants grow well and others don't. But, I suspect we would find articles about it if scientists had ever found that to be true. The published articles tend to be about terrestrial plants and are farm related. One of the experts in this hobby has often said that if allelopathy in an aquarium was real, it could be made to stop it's magic by treating the tank water with activated charcoal, to remove the chemicals involved, and then notice the repressed plants start growing much better.


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## tiger15 (Apr 9, 2017)

I think plant to plant allelopathy is rare, but exists as noted in at least this one plant.

https://aquaticarts.com/collections/bulb-plants/products/tiger-lotus-aquarium-lily-plant-with-bulb

However, I believe plant to algae allelopathy is possible and common, as a healthy planted tank has no algae. Before I had plants, I had bba on rock and hard surfaces in my fish only tank. From time to time, I had to take the rock out to bleach out the bba. After adding plants and balanced out, bba has disappeared on plants, rock and all hard surfaces despite higher light intensity. So some chemical changes must have taken place to make it uninhabitable for bba.


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## FromReefs2Plants (Aug 14, 2017)

Michael said:


> After 10 years of Walstad tanks, I've tweaked the method a little. I keep more fish than is optimal for the method. So I have lots of circulation in my tanks, mostly from power filters with mechanical media only. And I do change the water once in a while. If I am being diligent, a partial change once a month. My water is hard, so this helps with concentration of minerals from evaporation, and the build up of dissolved organic compounds. * If I am neglectful, there might be three or four months between water changes.* But fish and plants remain healthy and attractive.
> 
> I enjoy my aquaria, and do not feel like a slave to them. If life gets busy and the tanks don't get all the maintenance I would like to give, no catastrophes occur. And with a water change and a trim, they bounce back almost immediately.


I do the same and my tank still goes on and on and looks quite good while doing it.


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## gkai (May 14, 2018)

Regarding Anubias as emerged, it really makes a difference. Anubias are supposed to be slow grower, and they were in my tank, till they emerged. 
This tank was planned it as a riparium, so the canopy is huge ( I have a shallow, 40cm deep tank and 70cm of canopy) and planned some of the plants to become emerged, so I let the anubias do their thing.
Once out, in humid air with quite a lot of light (I deviate from pure walstad, using about 80W of led light for a 120x70x40cm tank), they are not slow grower anymore, instead they send roots everywhere, develop new leaves, and are cramped in my canopy! They took over the tank so much that I suspect they are part of the reason my other plants either wither or do not grow much...They probably remove most nutrients from the water, because even if other plants are struggling, there is not much algae in the tank and fishes are quite healthy. 
I got my krib cichlid couple reproduce and a lot of healthy fast growing little kribs (nice but also a possible problem: they are moderate territorial and burrow at least a little, so I guess I will have to gives some once near adult size...)

So yes, once emerged plants may behaves very differently compared to what they do fully immersed...


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