Bio-pellets: Update

Since the Vertex Biopellets have been used, I have gone from a relatively high PO4 down to an almost unreadable level and, currently, about 2 weeks after the extremely low reading, the PO4 has been creeping up again.  I'm not really sure why, but I get the feeling that my skimmer may not be efficient enough to rermove the bacteria waste in the amount that it is produced.  Otherwise, why would the PO4 rise in a 'nulled' system?  There have been no changes in feeding or inhabitants, no dead creatures, etc.  It would seem that, after the bacterial bloom that reduced the PO4, the skimmer is not removing all the bacteria and it is dying and the contained phosphates are being released back into the water column.

Next step, a new skimmer.  I have been planning on testing the Vertex cone skimmer, but need to redo the sump first.  Hopefully this will all happen in the next weeks, as I am also waiting for a new stand for the refugium part of the system.

I can't say that the corals appear to be suffering.  It is almost as if the biopellets do have an additional effect, which benefits the corals.  I had noticed a similar general improvement when I first started working with Zeovit.

The Carbon Cycle - Part 2

What is particularly interesting for us about the Redfield Ratio is that it gives us a clue as to how to control waste build-up in our aquariums.  Our aquariums are not a natural environment, however, the inhabitants will still follow the same rules as on a living reef.  We can be assured that the Redfield Ratio will still impact the system.  In the end, the chemistry doesn't change.

What does change is the unnatural amount of nutrient we add to our aquariums.  As on the reef, the nutrients reach a state of breakdown of ammonias and phosphates.  On the reef we find plenty of bacteria that will assimilate these wastes and remove them from the water column.  These wastes are not actually gone, they have simply changed their state by being incorporated into another life form.  Plankton!  Bacterial, plant and animal.  As we know, plankton is, also, a food source for many creatures.  Clams and other molluscs filter it from the water, as do sponges, tunicates, various worms, etc.  In an aquarium we rarely have enough of these filtering life forms to compensate for the wastes of our larger , non-filtering life forms, should we manage to produce enough waste product assimlating bacteria.

Going back a step to the bacterial plankton, we have learned that its production follows the Redfield Ratio, 16C : 16N : 1P.  In a typical aquarium, the wasteproducts containing nitrogen (ammonias:NH3, nitrates:NO3, nitrites:NO2) and those containing phosphorus (phosphate: PO4) are more common than carbon.  The aquarium becomes carbon limited and the levels of these waste products rises.  Without sufficient carbon, they cannot be converted into (bacterial) plankton.  Conversely, one may have sufficient carbon present from carbon dosing, but not enough nitrogen, which leads to a rise of phosphate,a common scenario in older tanks during changeover to a probiotic system.  One can, also, have a phosphate limitation, which will lead to the nitrogenous waste level rising.  Balance is the thing.

In an effort to maximise this cycle, we add a source of carbon to the aquarium water.  First experiments were made with alcohol, sugars and acetic acid (vinegar), amongst other chemicals.  This is based on a long used technology to treat waste water in water treatmant facilities.  It is really nothing new, simply the application is new.

Suffice it to say, these methods work.  Some a bit better than others, but, as each aquarium is a bit different, one cannot expect identical results.  What is clear is that pushing the Redfield Ratio reaction reduces nutrient waste levels in closed aquarium systems.  We don't know all the complex chemistry that lies behind this nutrient reduction, as this is not a simple path, rather a complex network of possible reactions that lead, via bacterial guilds, to this reduction.

Now, one of the first things one will notice, if they pour a capfull of vodka into a nutrient laden aquarium, is the aquarium water clouds overnight.  Often accompanied by the death of many, if not all, of the higher life forms.  Shock of shocks!  Well, one does learn from this, as it doesn't have to happen this way.

What has happened is that enough carbon has been made available for a massive bacterial bloom in this closed system.  In and of itself not bad, but, quickly reproducing bacteria take the oxygen out of the water so rapidly, that the higher life forms asphyxiate from lack of this life giving gas.  This is why one starts slowly to convert a standing aquarium to a probiotic system.

As I mentioned above, it is a rare aquarium that has enough filterfeeding organisms to remove the produced bacterial plankton.  This removal is mechanically done via a protien skimmer.  But that is another subject.

The Carbon Cycle

The carbon cycle is one of the true basics of life.  After all, we are carbon based organisms and carbon is the basic element of life on our planet (although it is theorised that silicon could also be used to base lifeforms).  Without getting into too much science (do a web search for deeper infos), the carbon cycle is the reason why we dose carbon to probiotic systems.

In the breakdown and reassimilation of waste products via bacteria, carbon leads the chain of events.  In an aquarium our main waste products are ammonias and phosphates.  Both of these products are nutrients, which is to say they are food for various organisms and plants.  Unfortunately, in large concentrations, they are deadly poisons.  One can remove them in various ways, such as regular large water changes with purified water, adsorbtion media, plants, such as alga, bacteria, amongst a few methods.  In a pro-biotic system we are using bacteria as our main assimilators.

An oceanographer by the name of Alfred C. Redfield noted that marine plankton world wide had a particular ratio of the three main elements of carbon, nitrogen and phosphorus.  Named in his honour, the Redfield Ratio states that C : N : P is very consistant at 106:16:1.  This is to say, for every atom of phoshporus, you will need/find 16 atoms of nitrogen and 106 atoms of carbon.  Although he was sampling complex plankton, which contains plants, animals and bacteria, the ratio remained the same.  This ratio sets the tone for carbon dosing as a waste neutralisation method.

to be continued......

Bio-pellets

This is one of the newest methods of carbon dosing a marine aquarium.  I've only been testing them for about 6 weeks, and have learned quite a bit about them.  I've been using the VERTEX Pro-Bio Pellets, which are made of 100% PHA polymer.  They are essentially the same as any other biopellet, having an extruded shape of a small cylinder, typical for extrusion plastics designed for the industry.

When first using pellets, it is suggested to soak them for a day or two in osmose water.  I can confirm that this is the best start.  I tried using them direct, to see what would happen and they tend to float to the surface of the fluidising reactor.  Typically, they give of, quite slowly, air bubbles, which make them bouyant until saturated with water. In retrospect, it may be a good idea to soak them in the reactor with tank water, letting them stand for 24-48 hours before turning the reactor pump on.

Water flow is critical to their proper function.  They need to be kept in constant, gentle motion in the reactor body.  I have found that, in a 2 litre capacity reactor, a maximum of 1.5 litres pellets should be used, with a flow of 1000-1500 litres per hour flow.  This will keep the pellets in constant motion, which assures that they will harbour only aerobic bacteria.  Should part of the pellets just sit at the top of the column, they will tend to become anaerobic or, perhaps better said, minimally aerobic, even though there must be a minimum of water flowing through them, it is the agitation that promotes the aerobic condition.

My tank is a long established 900 litre system previously run with ZeoStart3, glacial acetic acid and/or VSV as carbon source.  In order to better facilitate the changeover to pellets, I decided to continue to half dose my previous carbon sources until I was assured that the pellets were functioning.  As everything was not to go as planned, I'll explain what happened.

For the first few days, I was using a 1.5l reactor from Deltec with a 1000l Eheim compact pump.  The pellets did tend to clump a bit at the top and I never really got the kind of aggitation I wanted.  As I had no other pump at the time, I let things just run for 2 weeks to see what would happen.  In short, the pellets didn't seem to really kick in.  Those in good motion slowly paled, while the clumped ones becam a darker beige. Not truly dark, mind you, but enough of a colour difference to clearly see.  The aquarium water did not get cloudy, as expected from a bacterial bloom.  Although I was dosing carbon from previous sources, the PO4 level was slowly rising and stabilized at about 0.06 to 0.09, which is doable, but far from optimum.

I decide that the reactor was too small and that the pump was probably too weak.  I got a Vertex-20 fluidized reactor (universal filter) and a new 1000l Eheim pump.  In the new reactor I placed a total of 2 litres pellets.  I ran the reactor for 48 hours, but the entire amount of pellets couldn't be kept in motion.  Interesting to not, the new Eheim was much stronger than the older, identical model, and this was not because the older was dirty (yes, I cleaned it!).  Either they loose strength over the years, or are simply not all equal.

This wasn't really working, so I took out about 0.5l of the pellets to see and, voila, the pellets moved in a wonderful cascade of pearly white.  Looked like I had solved the technical side.  The pellets were in constant, gently mostion, moving the entireway up the chamber and cascading down again.  By the way, pellets will tend to rise on one side and fall on the other of the reactor.  This is fine, as long as all pellets are in motion.

I checked the PO4 as I made this change and it had reached a scary level of 0.15ppm.  Well, let's see what happens.  I stopped dosing other carbon source in anticipation of a full funtioning reactor.

48 hours later, I woke up to a tank with slightly milky water and a skimmer chruning up white foam.  Bacterial bloom! None of the tank inhabitants were stressed, so no great worries about oxygen depletion.  I checked the PO4 and it had dropped to 0.01!  Success.  The bacteria had kicked in and done their job.

This is certainly the best method of carbon dosing I have found.  You can't really OD on the stuff, as it doesn't dissolve, rather it is eaten by the bacteria in situ on the pellet surface.  I have discontinued any other form of carbon dosing, but, with the nutrients so low, I am dosing daily Amino Acids and Coral Vitalizer (Korallen-Zucht) at normal dosages for the products (8-9 drops daily).

I am making fotos of the various corals, as best as I can, to document changes in the zooxanthellae and colour.  I'll post fotos in the near future.

A preface

I f you've found this blog, you probably know what a Pro-Biotic filter system is about.  For those that are unsure, a brief introduction to the advancing world of natural process oriented aquarium maintainance.

A coral reef is a complex living entity, best compared to a tropical rain forest in it design and intertwined biology.  A myriad of life lives in these eco-systems and it is this complexity that even makes these systems possible.  They are stable and fruitfull, despite both existing in a nutrient poor environment.  Many think it is foolish to even attempt to mimic them.  Others, like myself, are always seeking new ways to pioneer our journey to a thriving and healthy reef ecosystem, and this with considerable success.  When I think of my first marine tank, some 40 years ago, the advancements in marine aquarology are staggering and a tribute to the many engaged aquarists and scientists involved over the decades.  It's just always getting better.

When we attempt to reproduce a part of a living reef in an aquarium, we are extremely limited as to how much of this complexity we can maintain.  Unlike a reef, an aquarium is a closed system, which, in short, means that it cannot remove its own waste products in the grand fashion of the oceans.  And we feed a marine system, which simply adds to the potential waste product enclosed within an aquarium.  I think we can assume all aquarists are aware of this problem, as this is typically that which kills-off our treasured tank inhabitants.  Whether directly via nitrate or phosphate poisoning, or diseases which find an opportunity to attack stressed marine creatures, water quality is the crux of a successful marine aquarium.  Light would certainly be the second most important factor, but I'll come to that later.

The oceans have evolved dynamic communities of creatures that exist from each other, whether from one fish preying on another or microbial creatures assimilating dissolved organic matter, we have a finely tuned symphony that allows life to continue.  Pro-biotic filter systems are out attempt to understand and harness parts of this system from mother nature and fine tune it in order to better apply it to our closed marine communities.  Yes, we are talking not only water quality, but the biology and chemistry behind this living liquid.

In this blog I hope to elaborate on the various approaches and experiments already performed, successful or not, in order to give an aquarist an overview of the current state of pro-biotic filters.  I will be discussing many of my own experiments, the failures and the successes which have brought me to a point whereby I can not only maintain my marine charges in full health, but understand how I'm managing it!