# The low tech concept and nutrient balance



## Navyblue (Jan 1, 2013)

A few years ago, I converted a saltwater tank to a planted tank. I wasn't new to fish, but I was new to plants in general. My primary objective was to have a fish tank that is extremely low maintenance, if not zero maintenance. Naturally I was attracted to the low tech concept. My goal was to have a tank where I only have to feed the fish and top off evaporation, and the plants will take care of everything else.

I wasn't sure if I could pull it off, my primary concern was, how can I make sure the output of the fishes is in equilibrium with the intake requirement of the plants?

So I got myself some Seachem Fluorite (for its low maintenance, I hated the look), some LED spot light, and a plethora of low light plants. After a while I figured what plants work in my tank and what don't. Long story short, I ended up with a tank full of Anubias. Low maintenance, and they just don't die.

Fast forward a couple of years to today, I have a better understanding of how my tank is working. In short, I did not achieve my original goal of no maintenance.

My personal assessment is that tank has a tendency to have too much N and too little everything else. With no water change and no fertilizing, the N will stay upwards of 50 ppm and growth is stunted. There are growth but the tank does not look good, the immersed Anubias leaves is a very dark green and the leaves curl downwards. The emmersed Anubias (has access to atmosphere CO2 and window light) is worse, All the leaves has brown tips (N deficiency? but I have too much N.) In one instance I notice growth days after dosing P and K, those new leaves are nice and of the right colour and shape.

So my personal experience with with fish poop and Anubias is at best a limited success. It could be that this particular plant species simply cannot achieve good nutrient equilibrium with my fishes' poop. What I would like to ask is your experience of running low tech tanks, how well did you get away with no fertilising? I have read that low tech tank have a tendency to run low with K, but what I did not expect is I seem to have a problem with low P too?

What do you think is my best course of action, add some kind of plant that will absorb more nitrate but less of other nutirent?


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## Blacktetra (Mar 19, 2015)

one way or another those elements will need to find their way into the tank for plants to grow well.
Even Tom Barr's low tech method recommends a little dosing of fertilizers. Not much, just a teaspoon or so depending on tank size. (If you want to know how much he recommends I can supply that info, but you can also just google "Tom Barr Low tech" and skim his large post for the fert dosing he recommends in there.)

The fact is, if you don't change the water, and all you ever add to the tank is distilled/RO water and fish food, then you're not going to give the plants everything they need. Mostly because fish food is designed for fish (and usually it's not all that super well designed anyway nutrient-wise) and once the fish have consumed it, they produce excrement that can only contain (for the most part) what was already in the food to begin with.

So if your fish aren't given food with potassium, I can't see the plants ever getting any. This is a ghastly over simplification of the biological system involved, but if you don't provide something for your plants, they won't get it.

Now some plants can do an amazing job of making due without some things. Just like your anubias have managed to make due so far. So if all your wanting is some plants that can better handle nutrient deficiencies then there are some options out there. But in the end is it really that hard to just buy $20 of dry ferts and dose a teaspoon once a week or two? Plants are happy, fish get fed so THEY are happy, plants absorb more N so fish may be healthier, seems good all around to me.

Bump: I suppose the only possibility that jumps to mind for getting a greater diversity of nutrients in your fish poop is providing a greater range of food to a greater range of fish species. Namely, do you have predator, omnivore, and herbivore species? I'm sure their poop would contain a greater variety of nutrients provided that you give nutritive foods to each kind that matches their feeding habits.


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## Navyblue (Jan 1, 2013)

I agree that the most straight forward way is to simply dose what is needed. I do this from time to time, just that I have yet to develop a routine, a large part due to my fear of overdosing without frequent water changes, but that is another topic altogether.

While I was thinking about changing/adding the plant part of the equation, you brought up a good point on changing the fish/food part of the equation. The main reason I ask about plant is that we often hear certain plants being recommended to absorb nitrate (say anacharis, duckweed, etc), it almost sounds like they need little else to grow. If they indeed use more N and less P and K (which I have no idea), it can potentially be a happy ending for me.

FWIW, I mostly have rummy nose tetra and cardinal tetra, but now I am transitioning to guppies.


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## Blacktetra (Mar 19, 2015)

While some plants are definitely considered nitrate hogs, that title seems to be mostly earned because they consume it FASTER than other species, not necessarily MORE. What I mean is that some plants simply consume a greater amount of nutrients faster than others. But that may not be the case when they aren't given a minimum of P or K.

I see my spare/temp/hospital tank drop in nitrate rappidly when I provide the other minerals to the duckweed growing there. When there isn't enough magnesium, calcium, phosphate or potassium, they seem to come to a near halt.

I also don't recommend duckweed unless you want it in the tank forever. It's nearly impossible to be rid of without a great deal of work. But perhaps someone else might know of a plant that does well with very little P or K.
The only plant I know of that can grow well with no fertilizing and very little care is java moss. I suppose you could give it a try, but again, most plants NEED at least SOME of these minerals.

If you follow Tom Barr's dosing guidelines in his low tech guide, what he recommends is an amount that really can't be overdosed. I've accidentally (and due to laziness) dosed my own low tech with very irregular scheduling, and I really don't do a water change more than once a month typically. And even then I've seen nutrient deficiencies, but never nutrient toxicities (caused by over dosing)
The amount suggested is so small you really can't easily overdose, and even when the amount is particularly high for what is typical (doubling the dose by accident for example) the plants usually eat through this fast enough.
Really what this dosing level does is gives the plants a weekly feeding that keeps them alive and healthy, but then they run out of food and patiently await the next dose. As a result you aren't constantly flooding the water column with high level ferts like in the EI method. Your giving just enough to keep things healthy, and when they begin to look poor, like your anubias do now, you simply go "oh, you're hungry, here have some P and K" and then walk away from dosing for a week, maybe even two.

Low tech is fine when irregular. Your at far greater risk of having unhealthy plants by UNDER dosing Tom's recommendations than you are of ever over-dosing unless you replace teaspoons with tablespoons.


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## Navyblue (Jan 1, 2013)

To think of it, the Walstad method doesn't work for me on my betta tank too, which has a different plant and fish. Similar symptoms too, high nitrate and stunted growth. My suspicion is that it is highly unlikely that fish poop would decompose to exactly the nutrient proportion that plants need. So overtime you will have a nutrient imbalance, most likely an excess of N, may be sometimes P too. It may work in nature, but with the fish flakes I feed and the plants I have tried, I have yet to find a working formula.

Until someone can enlighten me on that topic, I guess dosing is the only way to go. The method seems to call for 1/32 tsp of KH2PO4 per 20G per week, that's a tiny pinch for any reasonably sized tank. I guess I could do that. I also don't think I will be dosing any KNO3, I will try to increase my feeding first.

But for such a tiny amount it likely is easy to overdose. However for my emmersed Anubias, I suspect it is just as unforgiving and hungry as a high tech tank, considering it gets unlimited CO2 from the atmosphere. There was a time when I dose weekly trying to find out how much do I have to dose so that the leave tips will stop turning brown, I think I dosed like 3x the recommended dose on the bottle and I have not found out how much it really needs. So it seems to me is that emersed plants are especially against the spirit of low tech tank when your fish poop isn't all the plant's nutrient need.

Which leads to my original question, anyone managed to get no dosing to work? If so, what plants and fishes are those? It may be that me having a single type of plant causes the problem to be especially acute.


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## s_s (Feb 15, 2012)

1. One thing to keep in mind is soil interactions--soil in your substrate plays a key role in decomposing fish waste into substances that are biologically available to plants.

Given that anubias isn't exactly rooted, it's not positioned in a way to take advantage of the microbe-soil interaction. Particularly, as N rises in the soil, it will be converted by nitrifying bacteria to nitrate which plants have a much slower uptake rate, compared to ammonia. 

2. Plant growth is what offsets the food that enters your tank. If you only pick slow growing plants, you simply won't have enough growth to offset it. If you're constantly adding fish food to the system, you need to be constantly removing excess plant growth from the system. That's sort of the promise of the Walstad method--trimming is easier than water changes.

3. Anubias is already slow growing, but that growth is going to be carbon limited. You don't have any plants with the "aerial advantage", then you're not going to get enough Nitrogen uptake. Again, organics in the soil provide a natural source of carbon, but only if the plants have their roots in the soil. 

All types of swords will develop the root system to take advantage of the soil, and floaters like frogbit or water lettuce will suck nitrate thanks to their virtually unlimited carbon source.

tl;dr you likely already have plenty of nutrients in your tank for your plants, you just didn't choose a plant that's in position to take advantage of them.


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## Diana (Jan 14, 2010)

Plants need over a dozen elements to live. They cannot substitute one for another, they need them all. 
Some, they need quite a bit of:
Hydrogen, Oxygen, Carbon. 
Some they use a fair amount of, but less than the first three. These are referred to as macros. 
Nitrogen, Phosphorus, Potassium. 
The next group are secondary nutrients. 
Calcium, Magnesium, Sulfur.
The last group are usually lumped together and called micros. Plants use the least amount of these. If present in excess they can be toxic.
Iron, all the other minerals.
Fish food contains a fair amount of N, P, and most micros. If your NO3 test is showing high, and all you add to the tank is fish food, then you can assume that P and most micros are also available in abundance. 

Fish food is low in K, Fe, Ca and Mg. And carbon. 

If the water has a GH of at least 3 German degrees of hardness, then you can assume that Ca and Mg are in there. If you want to dose some GH booster just to be sure, go for it. Read the label and make sure it is a GH booster that does not contain salt (sodium chloride). 

This leaves potassium and iron (and carbon) as the first nutrients to dose in a low tech tank.

Before I went with the EI method, I dosed Leaf Zone (liquid fert with K and Fe), and Excel. 
When I started using the EI method I had to adjust the amounts because I still had a lot of fish in the tanks and was adding fish food. I ended up adjusting the EI recipe down to something like the PPS-Pro level. 
Here is how I did this:
1) Test NO3. Adjust the dosing of KNO3 until the NO3 is good. 
2) Adjust the KH2PO4 and CSM+B the same % as the KNO3 (ie: if you only need 25% of the KNO3, then only use 25% of the KH2PO4 and of CSM_B)
3) Add potassium. Use the EI dose of KNO3, but measure out K2SO4 instead. Or a bit less. 
4) Add chelated iron. Look at the original EI recipe for your tank. See the dose for micros? Multiply by 25% and use that much chelated iron. 
5) Use Seachem Excel per label rates, but do not do the 'loading dose' unless you are fighting algae. (You can dose the loading dose with a syringe, directed right into the mass of algae). 

Monitor the tank with all the tests you have, and watch the plants. Adjust as needed.


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## yakal (Sep 4, 2015)

one thing i learned about this hobby is that the more effort you put the better the outcome. I think NO maintenance to extremely low maintenance doesnt apply in this hobby. just my personal honest opinion. i say this with all due respect


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## randym (Sep 20, 2015)

Your nitrates are high enough to distress your fish. 

Floating plants might help. They get their CO2 from the air, not the water, so you won't have to worry about that.

You might consider PPS-Pro dosing. That does not require water changes, like EI dosing does. And you can dump it in once a week, if you want, rather than daily. (Start out with half as much as recommended. I think the recommended dose is for high tech tanks.)


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## Hoppy (Dec 24, 2005)

randym said:


> Your nitrates are high enough to distress your fish.
> 
> Floating plants might help. They get their CO2 from the air, not the water, so you won't have to worry about that.
> 
> You might consider PPS-Pro dosing. That does not require water changes, like EI dosing does. And you can dump it in once a week, if you want, rather than daily. (Start out with half as much as recommended. I think the recommended dose is for high tech tanks.)


Nitrates up to around 100 ppm has been shown not to harm the fish. That is too high, but not in the range where it damages the fish. That is one of the reasons why the EI method was developed.

If you dose PPS-Pro and you believe that the recommended dosage is too high for a low light tank, you are using the EI method, not the PPS-Pro method, so the level of nutrients will still increase until a water change is needed. Water changes are very beneficial to the plants and fish, except that tap water can contain a high CO2 level, and water changes using tap water can cause big enough fluctuations in CO2 level that BBA growth is triggered. But, if you dose Excel, at 2 ml per 10 gallons of water, every day, water change caused CO2 fluctuation doesn't cause BBA.


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## randym (Sep 20, 2015)

I'm trying to minimize water changes because they really seem to distress my shrimp. I used to do 50% a week, which didn't bother the fish at all, but the shrimp really hate it.


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## Navyblue (Jan 1, 2013)

s_s said:


> 1. One thing to keep in mind is soil interactions--soil in your substrate plays a key role in decomposing fish waste into substances that are biologically available to plants.
> 
> Given that anubias isn't exactly rooted, it's not positioned in a way to take advantage of the microbe-soil interaction. Particularly, as N rises in the soil, it will be converted by nitrifying bacteria to nitrate which plants have a much slower uptake rate, compared to ammonia.
> 
> ...



You missed the part where my emmersed Anubias is constantly showing severe signs of macro nutrient deficiency.


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## Navyblue (Jan 1, 2013)

Diana said:


> Plants need over a dozen elements to live. They cannot substitute one for another, they need them all.
> 
> Some, they need quite a bit of:
> 
> ...



Thank you for those info, it will take me some time to digest.

I use tap water, I can see scales forming on the water line, so I suppose I should be fine in the GH department. Although the water here is mostly rain water so they are on the soft side, but the accumulation over time should be significant. I also dose Seachem Flourish may be one or twice a year.

I see immediate growth after dosing P and K, which leads me to conclude they are lacking in my system.

I do have BBA on almost all of the submerged leaves. I have Excel, but I haven't decided on my next course of action, at the moment I am leaning towards dipping all the plants in bleach. But if Excel can work as well, why not? It's certainly is easier.


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## Navyblue (Jan 1, 2013)

yakal said:


> one thing i learned about this hobby is that the more effort you put the better the outcome. I think NO maintenance to extremely low maintenance doesnt apply in this hobby. just my personal honest opinion. i say this with all due respect



It's certainly true. Personally plants are merely a means to an end, which is to lower the need for maintenance. If they are helping me on balance I will keep them, the aesthetic is a bonus, but to be honest I don't keep them for the sake of keeping them. 


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## Navyblue (Jan 1, 2013)

randym said:


> Your nitrates are high enough to distress your fish.
> 
> 
> 
> ...



Thank you, I will look into that.

However I suspect dosing KH2PO4 would solve most of my current problem until another deficiency rear its ugly head.


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## Hoppy (Dec 24, 2005)

s_s said:


> Given that anubias isn't exactly rooted, it's not positioned in a way to take advantage of the microbe-soil interaction. P


Unless the anubias are tied to wood which is some distance above the substrate the anubias roots do extend into the substrate and spread out just as most plant roots do. Anubias need to have their rhizome above the substrate, but there is no reason why their roots can't be in the substrate.


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## Navyblue (Jan 1, 2013)

Hoppy said:


> Unless the anubias are tied to wood which is some distance above the substrate the anubias roots do extend into the substrate and spread out just as most plant roots do. Anubias need to have their rhizome above the substrate, but there is no reason why their roots can't be in the substrate.



Yeah even when tied on wood, they will eventually reach into the substrate. And about a third of them aren't tied on anything but simply planted into the substrate.


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