"Susceptible to manipulation..."

It's long been known in the aquarium hobby that various natural materials can be used successfully to manipulate the environmental conditions in our tanks. Why do we want to manipulate the environmental conditions in our tanks? Of course, it's to create optimum conditions for our fishes. And the art of environmental manipulation starts with the most basic of parameters, pH.

Probably the single most important measurable environmental factor which we can manipulate using botanicals is pH. Now, the idea of lowering pH with botanical materials is not at all  a new concept. Hobbyists have incorporated peat moss to help lower pH...in water with very low general hardness, for generations.

A question we get a lot around here is about the "water-softening capability of botanicals", to which I respond almost reflexively, "There is none." Botanicals will not help you soften hard water.

I believe that anyone who tells you this categorically simply does not have the correct facts. Ask them to explain how this process occurs. I'd like to know, 'cause I've found no evidence of this! 

To help make sense of it all, we need to all re-familiarize ourselves with the concept of carbonate hardness.

Now, before we get too far, I'll dispense with the necessary disclosure that my knowledge of water chemistry is quite basic, and I'm not asserting that anything discussed here is the "last word" on the subject. It's an explanation of some facts and ideas based on my limited college chemistry and understanding of these things from being a "practicing aquarist." At a certain point in discussion about this stuff with really knowledgable people, my eyes start to glaze over...There are plenty of you out here who could "school me" on this stuff, and I encourage your input on these more esoteric, yet very important aspects of the hobby. We will all benefit.

Ahh, back to that bit on carbonate hardness...

This is one of those terms, along with "general hardness" (GH), that we see bandied about all over the internet and in books and hobby discussions...It's super-confusing to me, as there are multiple ways of determining the hardness of water (in general, but for us it's for aquarium purposes).

"Hardness", is essentially a measure of the total concentration of specific minerals dissolved in the water, including calcium and magnesium, as well as other minerals like potassium and sodium. It is said that the concentration of these minerals in a given quantity of water contribute to the "hardness."

Oh, and what exactly is "soft water", anyways? In simple terms, soft water is water which has a relatively low concentration of calcium carbonate and other ions.

There are a few ways of measuring this.

As a reef hobbyist, I was long ago indoctrinated to utilize KH (from the german word "karbonate") to measure the carbonate and bicarbonate ions in a given aquatics system, which function as "buffers", and keep the pH from dropping. And KH is a component of GH, to make matters more confusing (KH can never be higher than the "general hardness" of the water because of this fact). And a lot of test kits will measure both...as if a guy like myself needs more confusion in his life...


Hobbyists really seem to want an inexpensive, "natural", or simple way too soften their water. Using some botanical-based stuff just seems like it would be so right, doesn't?

Yeah, it seems that way.

And there actually IS a possibility here, impractical though it may be...Our old friend and nemesis, the "OG" botanical material used in aquariums- peat moss!

We receive a ton of questions about peat moss...mainly, what it can do to manipulate environmental conditions- pH and hardness- in aquariums.There is a lot discussed about peat's ability to "condition" aquarium water. And, although some of the facts might a bit convoluted, there is some validity to this, believe it or not!

Yes, interestingly, it is known that our old and controversial friend, peat moss, has actually demonstrated some capacity to conduct ion exchange ( a process in which which unwanted dissolved ions in water are exchanged for other ions with a similar charge.) Ions are atoms or molecules containing a total number of electrons that are not equal to the total number of protons. (I know, if you're like me, that made your head start spinning almost instantaneously.😳

Think of it this way: Peat softens water by exchanging humic acids for magnesium and calcium.

It's actually true.

Peat effectively binds calcium and magnesium ions, while simultaneously releasing tannic and other acids into the water. These acids "work" the bicarbonates in the water, reducing the carbonate hardness and pH to some extent.

And it will tint the water as well, as we all know!

Interesting, right?

However, you can't just drop some peat into your tank and expect "Instant Amazon." This process requires "active peat filtration" (the water passing over over the peat itself) to make this happen. Of course, you could place some in the tank and just wait for the process to occur "passively"- but it will take much, much longer.

Being the curious, and occasionally reckless fish geek that I am, I played around with this idea once, to try to see if this does, indeed work.

And, well, it does sort of work.

However, it took a LOT of this stuff to do the job with this "dump and wait" technique. 

How much?

Well, a shitload, if you must know. (and I"m being technically accurate, too.)

Yeah, it took a shitload of peat, and a fair amount of time to reduce my Los Angeles tap water, with hardness exceeding ~240ppm and ph of 8.4 down to "workable parameters" of 6.4ph and a hardness level of around 40ppm. How much are we talking? It took a full 2-cubic-foot bag of peat, added to a 30-gallon plastic trash can, filled with with my tap water, over 8 days in order to achieve these parameters.

So, yeah. The idea does work. Not exactly efficiently, but it does work.

Based on my experience, you CAN soften water with peat to some extent if you're  dedicated to it, have time, the means to do it, and a willingness and ability to test your water. I've long ago lost that thrill that some people get from these types of "money-saving DIY!" methods. To me, I simply decided to forgo other indulgences, save my money for a while, and invest in  the RO/DI unit, and call it a day.

Yeah, an RO/DI unit isn't quite as romantic as dumping some peat into a barrel of water, but it's a helluva a lot more efficient.

My SpectraPure 4 stage RO/DI unit cranks out 80+ gallons of zero TDS, zero carbonate hardness water in a day. Now, one could argue that the rejection rate of RO/DI makes it less efficient- but hell, I water my garden with the reject water! And yeah, a unit like mine retails for around $300 plus USD, a lot more than a 2-cubic foot bag of peat, but the long-term, consistent efficiency, ecological "friendliness", and reliability is pretty obvious to me. 

All in all, for maximum efficiency, consistency, and control, just invest in an RO/DI unit and you'll create soft water with little effort and no mess.

Yeah, it IS a bit pricy to purchase an RO/DI unit, but well worth it, IMHO if your goal is to create soft, malleable water to use in your aquariums.

So, this long dissertation on peat was a roundabout way of discussing how you could accomplish some water parameter manipulation with natural materials. It's entirely possible. It just requires some realistic expectations, research, effort, testing, and work.

There are some botanical products which you could incorporate fairly reliably to lower pH in water with minimal carbonate hardness, like...cones.

Cones, such as Alder and others, have been used successfully for quite a few years by shrimp and fish breeders to lower the pH in their aquaria, as well as to stimulate breeding. Some claim that they provide some antifungal properties. I've seen claims of higher hatch rates for certain fish eggs when utilizing cones as "water conditioners" in spawning aquariums. Is there any merit to these claims? Well, there seems to be at least some anecdotal evidence that the cones (well, really- the humic substances that cones release) may offer some benefits.

More about this later.

What, exactly, is a "cone?"

To many of us "city folks", cones are those odd-looking things that fall off big old Pine trees in yards and parks, are cool to throw into the fire while camping ('cause they "crackle!"), and to throw at each other when you're a kid! Well, to science, a cone (known to botanists as a strobilus) is the organ on a plant that contains the reproductive structures.

At this point, I'm so tempted to make some sort of juvenile-sounding joke about how weird it was that we used to throw pine cones at each other- but I'll spare you. Anyways, cones come in male and female varieties, are well-studied by scientists, and have definitive charachteristics that make identifying each species. sex, and viability possible, but I won't bore you with those details right now!

So, as far as cones are concerned, as aquarists, we like them because they are known to contain those tannins and humic acids. And, as you know by now, here at Tannin Aquatics, we have a more than causal interest in stuff that "tints" the aquarium water and contributes to a more dynamic physical and aesthetic aquarium environment- and cones can make some important contributions.


First off, the varieties that we aquarists will typically use are Alder, Birch, and Casauarina. These have been used for aquariums for some time, each has their own "tint capability" and therefore, utility for our purposes! 

Alder cones are probably the "alpha dogs" of the cone-using world, and you'll find aquarists worldwide playing with them in their aquariums.We've been offering them to our customers for years, and they seem to be very popular. Hailing from the genus Alnus, there quite a few species found worldwide.

The varieties most commonly used in aquaria come from Northern Europe and The Pacific Northwest in North America. Alder trees are also known to have bark rich in tannins, so it's no stretch to conclude that the woody little cones also contain some tannins as well!


Now, Alder cones are small- typically only a few centimeters in length, varying by age and species- but they are powerful little "tinters!' It only takes a small quantity of these guys, steeped in water, to produce some decent color.  Now, of course, color is simply an aesthetic "measure", and has absolutely no correlation with the pH of the water. Please don't forget that concept!

However, in terms of pH manipulation, there are some possibilities here.

A study done a few years back by a Swedish hobbyist using from one to six cones in a glass containing about 10 ounces of "reasonably soft" tap water, with a starting ph of around 8.12, was able to affect a drop to 6.74 with one cone after about two weeks, 4.79 with 2 cones after two weeks, and an amazing 3.84 with 6 cones after the same time period! The biggest part of the drop in pH occurred in the first 12 hours after immersion of the cones.

This same enthusiast extrapolated that it would take about 330 cones to lower the ph of 100 liters of tap water from 8.12 to a respectable 6.74 in about 2 weeks, with nicely "tinted" water resembling, in the hobbyist's own charming words, "a cup of tea"- music to our ears, of course, yet not exactly a scientific recipe.

So, suffice it to say, these little cones do pack a considerable wallop! Of course, no hobbyist I know is going to toss 300 alder cones in a 25 gallon aquarium to try to drop the pH by 1.38, but this exercise demonstrates the "capabilities" of these innocuous-appearing little cones, and demonstrates the need to treat them with some respect and start very slowly when using them in our aquaria! Because, well- damn- we are dealing with natural materials and to try to ascribe them precisely-delineated capabilities is really speculative.

The other cone commonly used by fish geeks is the Birch cone (Betula sp.), which has similar, although not quite as pronounced an effect on pH as Alder, in our rudimentary recreation of that other guy's slightly more sophisticated tests! Birch cones are a bit larger and more elongated, which apparently doesn't have much correlation with their "capabilities" as a "pH reducer" in the aquarium, but it's an easy identifier. Interestingly, birch extracts (from the wood, mainly) are used in other industrial capacities, such as treating leather and in flavorings.


A given quantity of Birch cones do seem to render a slightly darker tint to the water than Alder, in our opinions, but as we all know from me shaming you, tint is NOT necessarily indicative of the pH of water. And remember, very hard water is unlikely to have the pH substantially influenced by a reasonable amount of any cones or botanicals. Softer water (like RO/DI), with little to no general hardness, is far more susceptible to pH manipulation via botanicals, in our experience.

In order to round out our collection of cones, over the years, we've sourced the rather attractive Indian Casuaurina Cone (Allocasuarina and Alnus sp.), which come from the beautiful evergreen trees found throughout Australia, Oceana, and as non-native introductions into the Indian sub-continent (which is odd, considering the "Indian" moniker in the common name, right?).

These cones are somewhat lesser known in the hobby in Europe and North America, but have apparently been used in Asia for a number of years in the same capacity as Alder has in Europe. These are handsome, "fat-looking" cones that actually look kind of different to us.

CONFESSION TIME: As much as I love the idea of using cones in aquariums, I must admit that, in my opinion, they hardly look "tropical", and are best relegated to the utilitarian role of "media", used to influence tint, cultivate biofilms and fungal growths, and to a lesser extent, to lower the pH of the aquarium water in filters or media bags away from the display.

I just think they look- well, how do I sound politically correct? Um, shitty- in aquariums. To me, nothing screams "NOT FUCKING TROPICAL" more than a bunch of Alder cones in the aquarium proper.

Okay, well, that's just me. Of course, we'll now see a 30% drop in cone sales as a result of this micro-confession-rant shaming people into thinking they're ugly or whatever...Damn it! 😆

A lot of hobbyists- especially shrimp  enthusiasts, don't seem to be bothered by the look of cones in their displays. It's about the utility. And, if you're going to keep cones in your display aquarium, the Casuarina are the best candidates for the job, IMHO. Their ability to reduce pH is not quite as pronounced as Alder, or even Birch; nonetheless, they can impact water chemistry and definitely can influence the tint of the water!  And more important, they have a very "faceted" surface which seems to cultivate biofilms and fungal growths quite effectively.

Shrimp seem to love that!

So, how many cones do you need to use in your tanks? I'd be doing you a complete disservice if I even attempted to tell you with any degree of authority. I mean, we've had a few "baseline" numbers that worked for us, but for the most part, we need to experiment. It's really a matter of what works for you, the individual aquarist. 

In general, cones seem to be ideal candidates to use in filters, media reactors, or just passively somewhere in your aquarium where water flows over them gently.  As mentioned previously, they certainly make a great foraging area for shrimp, and the many -"faceted" surfaces (known, interestingly enough as "scales" to botanists) do a respectable job of recruiting biofilms.

Since shrimp and some catfish (I'm thinking Otocinculus) seem to love foraging in them, one could conceivably even sneak in some pelleted foods into the scales, turning them into unorthodox, yet effective "feeding stations" for these animals, or other bottom-dwelling fishes which might be out-competed in busy community tanks. 

In general, the cones mentioned here are known to science to have rather significant amounts of tannins in their tissues. As with most plants, the tannins are theorized to be present in cones to protect the mother plant from predators. With the tannins, their usefulness as aquarium "water conditioning media" is easy to understand in that context, right?

However, the other properties attributed to them by aquarists and hobby industry people are a bit harder to substantiate, IMHO. Many hobbyists who use cones will speak of their alleged "anti-fungal" and "antibacterial" properties, with little more than anecdotal experience (or less!) to substantiate these claims.

Unlike Catappa leaves, which have been studied by scientists in Asia and elsewhere for fisheries use as antifungals/antimicrobials, and which DO have some phytochemical constituents that may be useful in treating and preventing infections, we're really operating on the basis of inference and even supposition that, because the cones seem to do what leaves do from a pH and aesthetic standpoint, they must also have these "therapeutic" capabilities, right?


We have to break really careful about that. 

Of course, those of us who trade in botanicals need to be responsible when assigning these "attributes" to the stuff we sell, and not everyone in the industry does. I see lots of vendors selling these items around the world, with descriptions that absolutely imply that the cones have all of these amazing capabilities and should be used to lower pH, treat fungus, hatch eggs, etc.

As you know, that kind of overly-generalized, sales-oriented hyperbolic stuff makes me want to vomit.

It was the same with catappa leaves.

The last thing I wanted to do when I started Tannin Aquatics was to get caught up in touting all sorts of unsubstantiated claims about these leaves and the substances they contain, so I did my best to ferret out just what the ”real deal" is here! It it was helpful for me to at least try to extract some practical information out of the many claims about these leaves.

For many years, Betta breeders and other enthusiasts in Southeast Asia added catappa leaves to the tanks and containers that held their fishes, and noticed a lot of positives…Those breeders who actually fought their fishes seemed to feel that, when their fish were kept in water into which catappa had been steeped, they recovered more quickly from their fight-related injuries.

It really wasn't until I found some scientific papers on catappa extracts which documented their anti fungal properties that I began to accept this stuff a bit more. It was a lot of really serious scholarly research based on actual fisheries work that helped me change my mind.  Some good, solid, replicable experiments. It's a far cry from the usual drivel that we see spouted by a lot of aquatics vendors. That kind of stuff doesn't do much to elevate things, right? Usually, it's just these grandiose pronouncements about the alleged "miracle" abilities of botanicals and that's it.

Back to the cones, specifically, for a minute...

As much as I would love to share their enthusiasm and faith that they can do these things, until scientific aquarium-use-specific research is done on them, I think it's best to consider them as a means to provide some color to the water, to add some pH-reducing capability under certain circumstances, and for their ability to cultivate biofilms.  

We should state that it is thought by some to have possible therapeutic benefits for aquatic animals, the extent of which is not fully understood.

And that's it.

Yeah, I'm a damn "buzzkill", I know.

Although I'm personally skeptical of some of the claims about cones, I would encourage responsible hobby-level experimentation with cones as a possible "homeopathic" remedy or "preventative" for fungus and other possible fish maladies for those who are interested (I'm not).  Look, as long as we are open-minded, record our results, and don't simply ascribe every good (and bad) thing that happens to our animals while using the cones to their "properties", it is certainly with looking into!

The number of shrimp breeders I've spoken with and read about over the years who do use cones (mainly Alder and Casuarina) in their breeding/rearing aquaria with good results makes experimenting with them  too tempting to simply dismiss!

And of course, we can go on and on about the humic substances and tannins which are released by botanical materials in general, directly into the aquatic environment. That's a legitimate, known "thing", documented by a lot of scientific study. 

In the end, the ability of botanical materials to manipulate the aquatic environment is wide open for research. It's more than just theoretical that they are capable of doing some things to the environmental parameters of the water they are placed in. And yet, more work is needed on a hobbyist level if we really want to understand how the physical aquarium environment can be influenced by them.

So, don't be afraid to roll up your sleeves and work with this stuff. There is SO much to learn that it's not even funny! We're really at the ground floor of our understanding of how to manage botanical-style aquariums, and every one of us has an important role to play, helping to dispel myths, develop and perfect techniques, and add to the body of knowledge of botanical-influenced systems.

Whatever your course is...stay on it. Stay bold. Stay creative. Stay curious. Stay undeterred.Stay active...

And Stay Wet!


Scott Fellman

Tannin Aquatics


Scott Fellman
Scott Fellman


Leave a comment