The continuing coolness of..cones!

We've been working on all sorts of ideas in our cool little botanical/blackwater aquarium niche, and it's neat to see so many techniques and practices yielding new and exciting results! Many hobbyists are discovering the manifold joys of "tinted" tanks, and some of the expression and work we've seen is amazing! What's really cool is that there many ways to get it. too! 

One of the easiest and most efficient ways to get the tint into our tanks is to use various cones steeped into our water.

It's by no means a new practice, and hobbyists have been using cones for years for just this purpose, incorporating cones from various deciduous hardwood trees, such as Alder (Alinus), Birch (Betula sp.) and more recently, Indian Casaurina trees to condition water for various species of fishes. These little cones, each which appears morphologically just a bit different, also seem to have slightly different effect upon the aquarium water in which they are steeped.

Now, some hobbyists and vendors have attributed seemingly "magical" powers to cones, such as the ability to cure fungal infections, reduce incidence of egg fungus in fishes, etc. You hear this a lot in shrimp forums and other specialty discussion groups, but it's seldom backed up with any hard scientific evidence. In fact, I've personally never seen any hard data to support this attribute, nor have I seen anyone recommend a "dosage" (either number of cones per gallon or mg/l of "cone solution") that can reliably and consistently achieve the affects enthusiastically attributed to these cones, so for now, I'll recommend them for what I feel are their proven "applications"- imparting visible tannins to aquarium water and providing some aesthetics, as well as supplemental feeding for some animals.

Let's take a brief look at the most commonly encountered cone types used in the aquatic hobby.

The most "traditional" standby, the "Queen of The Cones", if you will- Alder, is pretty potent from a tannin-producing standpoint, imparting a nice tint to the water at relatively modest "doses" (like 6 cones for every 10 gallons of aquarium capacity, in our experience). Of course, the amount of color they produce and tannins they impart is variable, subject to a wide range of factors, such as the characteristics of the tank water, etc., and has nothing at all to do with how much they can influence the pH and water chemistry of our tanks, so you'll have to experiment and use our recommendation as a good "starting point" for working with them. Alder seem to be the least "durable" of the cones we work with, breaking down physically after just a few short weeks. In addition to their "tinting" capabilities, they are often grazed on for biofilm, and fed upon directly be many Neocaridina and other ornamental shrimp.

Birch cones are an excellent, more durable substitute or supplement for Alder cones, as they seem to last a bit longer when submerged, and impart a similar amount of tint to the water when used at a "dose" of around 6-8 cones per 10 gallons of aquarium capacity as your "starting off" point. Being slightly more "durable" than Alder cones, they are really cool to use as "media" in a fluidized reactor to more thoroughly mix with the water and impart their tannins to it; they tend not to break apart as easily as Alder when used in this capacity. Like their counterparts, Birch cones are also "fodder" for many species of ornamental shrimp, which feed on the biofilms they might attract, as well as directly upon the cones themselves as they break down.

Casaurina cones are relatively new to the scene, and have a decidedly different "look" to them. Not that looks are important with cones, but they are easily distinguished from the Alder and Birch cones, looking almost like miniature pineapples! They pack a very respectable tannin-production capacity as well, and seem to last longest of all, both in terms of structural "integrity" and ability to continuously release tannins into the water. Their highly "faceted" morphology gives them a lot of surface area, which is good for both releasing tannins and for providing a feeding "substrate" for shrimp and perhaps some xylophorous fishes (We've seen Loricariids of various species feeding directly on Casuarina and other cones on many occasions), recruiting biofilms in lower flow environments, and working well in reactors and such.

Carambola Lixo is our fancy Portuguese name  (referring to their "Starfruit-like appearance!) for what is actually a small fruit, in botany terms, from the Terminalia paniculata tree. We consider it a cone for our purposes and uses, and it can be used much the same way as the "traditional" varieties. Oh, and for those of you botany geeks, this tree is a relative of Terminalia catappa- the much-loved Indian Almond tree!  And these fruits (man, I want to call them "cones") are known to contain significant amounts of tannins, often used for dye in their native Southwest India range. They're light, long-lasting, and shrimp love 'em, too. Oh, and they sink almost immediately after submersion, which is something you wouldn't expect from them given their seemingly delicate appearance!

No doubt, there may be other cones that we encounter in the future which can suit our needs, and we will be sure to update you on their specific prep techniques and applications as we gain more experience with them! In general, the preparation of most aquarium-friendly cones is similar, however.

Preparation of cones for aquarium use is an important step, as they can accumulate a lot of foreign material (mainly small particles of dirt and dust) which should be removed before submersion. This is easily accomplished by a quick rinse in warm water. Being ever cautious, we also recommend that you "steep" them a bit (like 20 minutes or so) before use in some hot water. This will soften them up a bit, making the release of the bound-up tannins contained within their structures a bit more rapid. Some may say the steep is unnecessary, but being the conservative types, we "do the steep." Oh, and they smell amazing when they're wetted for the first time- you wouldn't want to miss that!

Utilizing cones in your aquarium is pretty straightforward. There are essentially three ways that you'd want to employ them. First, you can simply toss them into your tank after preparation.This is easiest and most common approach, although many aquascapers may not like the aesthetics. I personally think they look "out of place", myself...but that's coming from a guy who tosses leaves, palm fronds, and seed pods in his tanks, so "consider the source", as they say... Obviously, if you're a breeder or shrimp keeper/breeder, the aesthetics may be a secondary concern, so it's your call here. And of course, if they're being used as a Pleco or shrimp "chew toy", this is the most logical approach!

Over time, as they break down, the cones will recruit some biofilms on their surfaces. Of course, if you keep lots of shrimp or grazing fishes, the cones probably won't last long enough for this to happen! Shrimp, especially, seem "magnetically" attracted to them, and will travel all the way across "barren" substrate to get to them! It's funny to watch. 

The other way to employ cones is to use them "passively" as "media" either in your canister filter or other part of your aquarium where the water will flow through them easily in a mesh media bag. This gets pretty good water "flow through" over the cones, taking great advantage of their tannin-releasing capacity. The important thing to remember when using cones in a "passive" manner is to make sure that there is enough "void space" in the media bag to allow water to pass through and hit as much surface area as possible, to take advantage of the tannins locked up in their tissues.

Finally, you can place them in a reactor, as outlined above, which gives superior utilization of their surface area and ability to release tannins into the water column. There are a number of different inexpensive in-line reactors on the market that you might want to investigate for this application. Again, the caveat here is to allow enough "void space" within the reaction chamber to give the water a chance to pass through as much of the surface of the cones as possible. And of course, having that extra space in the chamber allows the "media" (cones) to tumble, creating an optimal water-to-media "exposure ratio."

As 'tint vehicles", cones are pretty cool little "packages", providing a fair amount of "bang for the buck", ease of use, and effectiveness. The amount of tint they impart to the water may not be quite as significant as say, Catappa leaves; however, they contain a nice "dose" of tannins, making them a viable alternative once you figure out the amount you need to do the job in your particular application. Sure, they might not create dramatic ph-reducing effects for you, so experimentation is always recommended.

In our experience, and the experience of many other hobbyists over the years, depending upon the volume of your tank and the starting ph/GH of your water, it is definitely possible to impact these parameters by using cones as a "media", making them practical, affordable, natural alternatives to chemicals and such for those willing to do their "homework."

So, there you have a  very quick "refresher" on using cones in your aquarium. With their small size, versatility, and relative "longevity" when submerged, cones are a great alternative to leaves when you want the  "tint" but you don't want these materials within the aquarium itself. As usual, these "practices" are constantly evolving, and the stuff related here is certainly not the last word on the subject! If you have other thoughts or techniques on employing the various cones for aquatic use, we'd love to hear from you!

Stay curious. Stay creative. Stay engaged. Stay "tinted!"

And Stay Wet.


Scott Fellman

Tannin Aquatics

Scott Fellman
Scott Fellman


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