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An algae and fert free solution to keeping fish tanks

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For fighting diatom algae and cyano, common advices are to lower the light or turn it off, more filtration or flow, raise CO2 and a lot of other peculiar, not working, tricks since they don't alter the reason for the algae.
GSA (Green Spot Algae) is another problem, people often give up fighting or don't really have a solution for.

I have made a discovery concerning the above that I wan't to share with you. I've already described it on a Danish forum, but it doesn't have many visitors. Feel free to pass this information to help your fellow aquarists!

To begin with it's not really a discovery since similar solutions are already used in agriculture, for removing algae from lakes and cleaning water for phosphorus at least in Denmark, but I haven't seen it mentioned anywhere for aquarium use, so the "discovery" is more like realizing it goes for tanks too.

I have a 250 litres tank with granite substrate. I had big difficulties with plants producing "air roots" (roots growing upwards from the substrate into the water) and lots of GSA. At the same time I had lots of diatom algae growing on the substrate, plant leaves, tank walls and decorations. Water changes only made the diatoms bloom again. Air roots and GSA are signs of phosphate deficiency while diatoms and cyano bacteria are signs of too much phosphorus compared to nitrogen in the water - a little hard to understand!

For half a year I dosed ferts without any result. I then added a lot of red clay-sticks:

Food Rib Wood Cooking Cuisine


under the plants' roots and also stopped using ferts. Now, half a year later, all diatoms and cyano bacteria are gone and the plants no more have GSA (or any other algae).

I also have a 54 litres tank with substrate taken from the beach containing lots of shells, lime stone and other stuff contaning CaCO3:

Plant Terrestrial plant Aquatic plant Flower Leaf vegetable


In this tank I've never seen any other algae than normal green algae which I find rather natural and decorative. Green algae are not poisonous and willingly eaten by fishes, snails and shrimps:

Terrestrial plant Organism Natural landscape Grass Plant


So my suspicion that the lime made the difference between these two tanks resulted in a lot of experiments and searching for information. Here's the explanation I've come up with. It might not be really scientific, but nevertheless fits with known physics and observations made on the two tanks mentioned above:

In an aquarium with a granite substrate, which is probably the most common substrate used, fish feces and rotting plant material will over time form mulm, which builds up in the substrate.
This mulm is known to have a negatively charged surface.

Potassium, magnesium and nitrogen in the form of ammonium (K+, Mg+ and NH4+ resp.) are all positively charged and hence will be attracted by the substrate and stay there ready for the plants to use via the roots.
Most nitrogen will exist in the form of nitrate (NO3-) though because of nitrification bacteria's breakdown of ammonia, ammonium and nitrite to nitrate. Nitrate doesn't bind to the surface of the substrate since it's negatively charged and therefore instead repelled by it.

Phosphate is also negatively charged (PO4-) and therefore repelled by the substrate, BUT!: this can be changed in several ways and easily.

An interesting discovery about cyano bacteria is they are present in all free water on the Earth's surface. Whenever the socalled Redfield ratio (about 16 nitrogen atoms to 1 phosphorus atom) tilts too much towards phosphorus, the cyano bacteria will bloom until the Redfield ratio is reached. Diatom algae often live in symbiosis with cyano bacteria which besides oxygen produce ammonia which is quite poisonous to living creatures like fishes, snails and shrimps. In fact I killed two large batches of shrimps before I realised the reason, feeding the shrimps with algae whereof most were cyano bacteria. Don't do this at your home!

Granite substrate doesn't contain much to attract the phosphate. Red clay contains about 3.5 % aluminum- and iron oxides which the phosphate will bind to. This must be the reason why all the algae disappeared. A more efficient way of binding phosphorus is using chalk, lime stone or the like containing about 100 % CaCO3. It does have a disadvantage though since it will raise the kH and pH somewhat. The higher pH will also reduce the uptake of free CO2 causing the plants to grow slowly, but this is easily overcome by adding a little CO2 from a yeast reactor.

Red clay also has a disadvantage since it makes my crypts dark colored - it could be the high content of iron causing this, but I'm not sure - yet.

Other metal compunds will bind phosphate, fx iron sulphate and aluminum hydroxide. The advantage of these over lime is they are pH neutral. Since the iron suphate will probably make my crypts dark too, I've started an experiment with using pure granite substrate with aluminum hydroxide added to do the phosphate binding. Actually I also added som talcum powder (appx. 32 % Mg and 63 % SiO2) to prove that a high content of silicates is not enough to make diatoms bloom as it's often said..
This experiment has only run for 4 days so I haven't a conclusion ready for you yet, but so far the snails, shrimps and daphnia I put in are not showing any sign of poisoning and I've not seen any algae so far.

The thing with aluminum is it becomes quite toxic at extreme pH levels, but the aluminum hydroxide has been tested safe for use at pH levels between 6 and 9 before it was used to cleanup Danish lakes. If it was poisonous in aquariums, the aluminum oxide in red clay would also be toxic, and I have had no problems with red clay in this respect. You probably should avoid aluminum in soft water tanks though since the pH could sink below 6 in such tanks!

So so far my suggestion is to use some lime stone powder. It's available for removing moss from your lawn and probably very cheap also where you live! Over here in Denmark it's about 4 dollars for 20 kilos. I crush it in a mortar to be sure to remove any bigger particles. Most particles are microscopic giving it an enormous surface and as such makes it very effective for binding phosphate. I put 1 (one) gram for every 50 litres of tank in a cup of water and stir well. Then it's just to spread it on the surface of your tank.

The water will be milky for about a day while the lime powder binds the phosphate and sinks to the bottom. After the treatment your water will be amazingly clear though and maybe clearer than ever. If you have a pH-meter it's a good idea to measure the pH before the treatment since CaCO3 is a macro nutrient and therefore will be taken up by the plants over time. When the pH then gets back to the original level you just add some more. Also monitor the plants for signs of phosphate deficiency and the water for high phosphate levels.

One more thing I'd like to share is this: I've stopped using filtration in my tanks. A filter will act much like your soil, meaning important nutrients are removed from the water. The plants do a much better job in cleaning your water and are surely prettier to look at! I have found no evidence that flow helps anything though many people recommend it, so the only flow I now use comes from an aeration stone.

Also notice I don't have to use ferts anymore! An average population of fishes, snails and/or shrimps in a well planted tank produce enough nutrients for the plants, of course dependent on the amount of plants, level of lighting and use of CO2. Feces are said to be low on potassium, but since my plants look healthy it's not a problem, maybe because I feed my fishes entirely with living food like daphnia, blackworms and grindal worms. In animals the potassium is mainly found in bone structure, teeth and the skin I believe, so that could be the reason. Flake food is normally made from algae and some kind of dried animals, so it should contain enough potassium, but I don't know for sure.
In a heavily planted tank with no animals of course you'll need to add ferts of some kind.

Hope this helps you, and please spread the word!

Dane William (that's not my real name)
Published 2016-10-01

Edit: corrected some typos. If you find errors or frases that could be misunderstood, please let me know.
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Discussion Starter · #2 ·
A picture of "air roots" on a crypt and a Nymphoides sp. "Taiwan":

Plant Terrestrial plant Wood Grass Terrestrial animal


These roots can be quite long - up to about 10 cm.

Wiki on cyanobacteria which actually can produce one of the most poisonous toxins known.

A Dutch page in English
about what happens when the "Redfield ratio is out of order".

Wiki on the Redfield ratio.

I've never seen air roots on anubias which leads me to the assumption that they are fully dependant on getting the phosphate through the soil. Anubias is the type of plant which quickest gets GSA in my experience and phosphate deficiency then leads to BBA and staghorn on the leaves. As can be seen from the picture in #1 it is possible to fully avoid GSA via the use of a substrate with limestone and shells.

Of course gravel from the beach is not exactly the same all over the world so here's a picture of mine separated in two piles with gravel containing and not containing lime:

Wood Ingredient Flooring Cuisine Mixture


On the far right I've tried to make a pile of eggshells which could replace the limestones. Because of the surface of eggshells being much smaller than that of powdered lime, you'd end up with about 35 g/10 kg. One (standard European) eggshell weighs about 7 grams.
 

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Have others tried to duplicate your results? That is what it takes before a theory can be taken very seriously. What would you suggest as a standard experiment that would show that this is a correct theory?
 

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Discussion Starter · #4 ·
Hi Hoppy. I'm getting old, so I've had fish tanks for about 52 years.
When I was a boy I built my own tanks and bought used ones and at a time had over 30. The money were small though so I simply had to find a cheap solution and this was getting the substrate at the beach.
So I've used beach gravel for almost 50 years without having to fight algae in these.

Then, some 35 years ago, I bought the 250 litre tank which came with the granite gravel and all the problems with a lot of different types of algae began. It was rather frustrating to have both a lot of algae free tanks and then the problem child, but I knew I was staring at the answer without knowing it. So my theory is my best shot on a possible explanation. I can't say that I know of anybody else using beach gravel. But in Denmark it's common to use red clay with sphagnum as a bottom soil and it works perfectly except it'll make your crypts dark of some reason. But it does help you keeping your plants algae free without affecting the pH. You could still have (very) little staghorn growing on the substrate though.

With the beach gravel I don't have staghorn on the substrate, but I once experimented with adding a little sugar as a replacement for CO2 instead of using liquid CO2. I was told it would work on a forum, but all it did was giving me an outbreak of staghorn growing on the substrate - none on the plants though. The solution was adding 8 times the normal dose of EasyCarbo twice. This killed the algae and then I simply changed the water to get rid of the sugar, I've not seen any staghorn since.

Our tap water has a pH of 7.6. In the tank with beach gravel I measure a pH of 8.3 which is lowered to 7.8 when adding CO2 from a small ½ liter yeast bottle reactor. I've had a lot of different fishes and shrimps in this tank not showing any sign of illness.

So if it doesn't matter you get a higher pH I'd suggest using 35 grams of eggshells per 10 kilos of substrate.
An acute treatment is using lime powder which will bind the phosphate currently in the water. This method makes it easier to monitor and change the pH as well.

If pH matters you could use red clay in the form of sticks (pencil thick). You should use about 500 grams per 10 kilos of substrate. I haven't tried using blue clay, but since it has less iron and more lime, it might work better.

There's no reason to be afraid of trying these methods as both clay and lime is present in the soil all over the world and as such also in lakes and rivers. The problem with algae in fish tanks arise when we use only one sort of material as substrate. Adding clay or lime or for that matter a little plant soil or sphagnum like the Walstad method suggests is actually closer to nature than not doing so.

Using the Walstad method with plant soil means you probably won't experience signs of phosphate deficiency, but the plant soil might not be balanced according to the Redfield ratio and hence give an outburst of diatoms and cyanobacteria.
Many people trying the Walstad method have reported this. I wouldn't dare to recommend the use of lime in this case since the soil will continue to pump too much phosphate into the water and you might end up with too much lime.

Let me also add that using lime or clay will have a certain max capacity for binding the phosphate. When that capacity is exceeded you might not get GSA because there's no deficiency, but you'd probably see diatoms and cyanobacteria again.
This means algae are not all bad since they clearly signal problems in the tank.

Let me show you what I mean by 'making my crypts dark'.

Here's the color of a C. Becketii which have no soil - the roots get all their nutrients from the water:

http://www.plantedtank.net/forums/attachment.php?attachmentid=677401&thumb=1

And here's how they look when planted in the granite substrate with red clay added (the dark greenish one):

http://www.plantedtank.net/forums/attachment.php?attachmentid=677409&thumb=1

They are nice and look healthy enough of course, but I'd like to have some light green ones.
 

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Discussion Starter · #5 ·
I have dug into my archive to show you how my plants looked some 2½ year ago before starting with red clay in my 250 litre. Like many others I had severe GSA on the plants, and at some point also an outburst of staghorn like this closeup shows:

Natural environment Plant Organism Fish supply Wood


This is when I redid the tank. The substrate was cooked and I added red clay plates under the substrate and began using ferts. From then on I didn't get any algae on the plants, but, as mentioned before, my crypts turned darker.
My other plants aren't affected so it could be a crypt-thing. Since the dark crypts actually look healthier than the green ones with a thicker cuticle, I might be on the wrong track. But if you see the whole picture:

Water Plant Plant community Botany Pet supply


you maybe agree it would be prettier with the C. Affinis in the middle to be light green instead of dark brownish green.- anyway that's what I'm after.

So with both red clay in the soil and using ferts I never saw any algae on the plants. But because of the dark colored crypts I redid the tank once again about a year ago. This time I used some new granite gravel called Råda Sand which has a little smaller size grains. This time I didn't add red clay, but I still used ferts.
Now I got GSA on the leaves and the C. Affinis didn't look healthy. I also had a little staghorn or BBA on the leaves. Then I stopped adding ferts and instead put red clay sticks in the substrate to get healthy plants over light green crypts and got rid of the algae.

That's how I can tell it's the red clay working and not the ferts.

I'll suggest everybody having plants with severe GSA and BBA/staghorn like I had should give red clay or limestone a chance since they have nothing to lose.
 

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Discussion Starter · #6 · (Edited)
I've tried to dissolve 5 grams of lime powder in a glass with 2 dl of tapwater with a pH of 7.6.
After that I shaked it couple of times and let it settle:

View attachment 678425

According to Wiki lime powder should have an alkalinity of 9.
But when I now measure the pH in the water I only get 8.1 which must be due to it's low solubility (0.013 g/l).according to Wiki.

I take this as a sign it's safe to use lime powder instead of eggshells in my recipe. The bigger surface of the lime powder will make more readily available to the plants. The good thing about the lime powder is it can be added to an existing tank so you'd not have to rearrange it. If you fear for your fishes you could of course remove them until the powder has settled. I let mine stay and have no signs of damages, but please don't sue me for this.
 

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Discussion Starter · #10 ·
As you can see from the second picture in #1 from my 54 litre with beach gravel I don't have algae on my plants and only green algae on the substrate as described.

As you can see from the closeups in #4 I don't have algae on the plants in my 250 litre either. I do have some thread algae left on the substrate near the front. I take guess it's because I was a little lazy when placing the red clay sticks since I only stuck them under the plants and not in the free spaces. I've tried adding som lime powder where the thread algae are, but they don't disappear from one day to another. So yes, my 250 litre has some thread algae on the substrate near the front.

Sounds to me like you don't like snails and crypts? I like snails and prefer crypts over a lot of other plants, just want them greener.
 

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For fighting diatom algae and cyano, common advices are to lower the light or turn it off, more filtration or flow, raise CO2 and a lot of other peculiar, not working, tricks since they don't alter the reason for the algae.
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If your going to name a thread "An algae and fert free solution to keeping fish tanks" that is a pretty bold, broad statement you'll need to show a lot more than some crypts before you dismiss some of the things quoted above.

You need to at least show a few full tank shots with a multitude of plants growing healthy and algae free.
 

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If your going to name a thread "An algae and fert free solution to keeping fish tanks" that is a pretty bold, broad statement you'll need to show a lot more than some crypts before you dismiss some of the things quoted above.

You need to at least show a few full tank shots with a multitude of plants growing healthy and algae free.
I have to agree with Houseofcards. I really do not mean to be offensive, but a tank with green algae and thread algae on the substrate is not algae free. And let's face it, most crypts will grow in the dark, and need very little in the way of ferts.

That being said, I'm always interested to hear new theories, and it's interesting to see how it's working in your tank. I'm just not sure what you are showing is very persuasive to support the title of your thread.
 

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Discussion Starter · #14 · (Edited)
I agree with you both. A better title would've been "A solution for keeping your plants free of algae without need for ferting" or the like. According to the Redfield theory you either have diatoms and cyano OR green algae except you can hit the excact ratio of 16 N per 1 P. You can of course still use ferts if you can't be without them.

My solution simply pulls the phosphate out of the water and binds it in the bottom where the plants can use it. As mentioned before it gives me some green algae on some of the stones on the substrate, so it might not be perfect for all, but I don't mind the green algae since they are food for my shrimps and some of the fishes.

I didn't bring a full picture of the 54 litre since I find it hard to see the details, but here's one:

Plant Aquatic plant Wood Rectangle Grass


How's that?

Bump: When the talk is about the light, I've made a mega thread on our forum and also experimented to find the optimal light. Furthermore I've optimized my lamps to get the most out of them, but I'll keep the light out of this thread. I might make another thread about light though.

Edit:
Bump: You'll probably argue that anubias is an easy plant as well. I totally disagree since people with BBA problems often show their anubiases drowning in algae, so for me a clean anubias is the best proof this solution works as described (or elsehow, but still works).
 

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...My solution simply pulls the phosphate out of the water and binds it in the bottom where the plants can use it.

Bump: You'll probably argue that anubias is an easy plant as well. I totally disagree since people with BBA problems often show their anubiases drowning in algae, so for me a clean anubias is the best proof this solution works as described (or elsehow, but still works).
Why can't the plants use the phosphate in the water column?
 

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Discussion Starter · #18 · (Edited)
I can't say that I know why. Some plants try by developing air roots to get hold of the phosphate in the water. Anubiases seem to be unable to do so, but though they can grow submersed they're not true waterplants as is the case with fx Vallisneria. In short GSA is a symptom on phosphate deficiency so plants with GSA haven't succeeded getting enough.

I do have an anubias that doesn't get GSA:

Plant Leaf Organism Leaf vegetable Aquatic plant


This one has just been floating in a breeding tank for years and I never saw GSA on it though I don't use ferts in this tank and also don't use a substrate. In fact it's what brought me to my theory since I have different implementations which each gave different results.

Floating in the water this anubias can still get phosphate through the roots since all nutrients are present there.
 
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