Probiotic/beneficial bacteria for improving water quality and nutrient control

Probiotic or beneficial bacteria, in general, are used to improve water quality through degradation of solid and dissolved wastes.

These strains of bacteria are usually Heterotrophic bacteria, and there are many different strains that are used that perform specific jobs in the Aquarium.

These bacteria CAN, be naturally occurring in the aquarium, and if regular cleaning and water changes are performed, the natural bacterial population may be large enough and effective enough to control solid and dissolved wastes, but in most cases, the aquarium needs a little help.

These heterotrophic bacteria reproduce so quickly (every 30 minutes or so) that not only do they very quickly eat themselves out of a food source, but the rapid cellular reproduction means they they mutate into less effective forms of the strain they first started as,  and become less and less efficient at the job they do.

More often than not, probiotic bacteria need to be dosed every 7-14 days in a closed system like an aquarium or pond, depending on the type, brand and effectiveness of the bacteria. These Bacteria usually have a wide range of salinity, pH and temperature they will operate in, and most often than not will opperate in both freshwater and saltwater aquariums, although some bacteria will be more effective in either fresh or marine environments, the majority of heterotrophic bacteria (and even some Autotrophic bacteria, such as those responsible for nitrification such as nitrosomonas, nitrobacter, nitrococcus, nitrosococcus, nitrospira, nitrosospria, nitrosolobus) will operate in both fresh and saltwater

The strains included in most good probiotic bacteria supplements will be chosen because they are very effective at specific jobs, such as organic waste reduction, nitrate reduction, phosphate reduction, disease suppression etc.

And so, by adding these bacteria every week to two weeks, you keep a good colony of efficient strains of bacteria in your aquarium suited to reduction of waste, and therefore your tank stays cleaner, for longer.

Dosing in freshwater Tanks:

Although dosing for every tank is going to be different, generally you can judge the dose rate needed by the level of solid waste in your substrate, and the nitrate levels in your aquarium. Most manufacturers will provide detailed dose rates for their Bacteria cultures and these are good starting points.

Using these two indicators to determine dose rates obviously will only work with bacterial mixes that actually reduce nitrate and solid waste and you will need to try for yourself to determine which bacteria is the one for you.

At the start of dosing, having an idea of waste levels in your substrate and nitrate levels will give you an idea of how well a given bacterial mix is working in your aquarium. Using a dose rate that well and truly reduces these waste products to start with will then allow you to "work backwards" and determine a dose rate by measuring your nitrate levels and monitoring your water clarity and level of waste in the substrate, once either of these indicators start to increase, simply increase the dose rate slightly until you no longer have either problem and you can continue dosing from there.

Strangely enough, compared to marine aquariums, enough organic carbon seems to be liberated from the breakdown of organic waste to fuel the waste reduction process and dosing more bacteria seems to be better (to an extent). Perhaps this is due to the breakdown of the bacteria that have previously digested the waste products releasing organic carbon that is then taken up next time by bacteria when it is re dosed, much like PHA (or similar compounds) based Bio-pellets used in Marine Aquariums.

Although there is still a certain amount of waste that is leftover after dosing and running a course of pro biotic bacteria in freshwater aquariums that need to be removed manually, the amount of this waste compared to what would be present without dosing is orders of magnitude less.

The reason this doesn't work that well on a consistent basis in marine aquariums in my opinion, is because the biological recycling or nutrients is much more complex in a marine environment, and therefore consistent breakdown of waste and dead bacterial cells, if not removed by protein skimming, is taken up by other organisms (which may not be beneficial in a marine aquarium, such as cyano bacteria), or will simply breakdown into the waste by-products (to an extent) previously digested and only reduce nutrient so far, and since low levels of nutrient are required in most cases for reef systems, more "enhanced" and effective removal of these bacterial cells is required to maintain a higher level of water quality. But more on this later.

Dosing In Marine Aquariums:

Dosing In marine Aquariums, as mentioned above, when not using a protein skimmer will only get you so far, but it will still work, I use a Bacterial product in my 25 liter skimmer less nano and it maintains close to zero nitrate and phosphate levels around 0.5ppm, this is enough to encourage some corraline algae growth, however does not enhance water quality enough to keep SPS corals or some corals that require a higher standard of water quality.

To remove enough of this bacteria to reduce overall waste levels, not only does the bacteria have to be efficient enough to break down and digest the majority of the waste in the first place, but you also need to remove as much as the new biomass that is produced, in order to harvest the nutrient locked up in its cell structure, otherwise, as is the case in freshwater systems, the bacterial biomass left over breaks down and nutrient removal slows down, this is not so much of a concern in a freshwater system as generally, most inhabitants are able to endure levels of phosphate, and other waste products without any long term issues, and the low levels of waste achieved by using a Probiotic bacteria are FAR lower than usual, and thus, enhanced removal is not really necessary.

Unlike dosing in freshwater systems, in marine systems, bacterial dosing is usually used in conjunction with organic Carbon dosing, as mentioned in my previous blog post, organic carbon accelerates the reproduction of bacteria to increase the speed and amount of nutrient uptake. Therefor it makes sense, that if accelerating the uptake of nutrient, for the most effective nutrient removal you should use the most effective bacteria by using a probiotic bacterial mix that contains bacteria chosen to be efficient at specific types of waste reduction.

However, when using organic carbon to accelerate bacterial production in marine systems, less seems to be more.

Even though it seems to be extremely beneficial to dose probiotic solutions in marine aquariums, dosing less bacteria seems to achieve a better result, and I have a theory as to why.

As you know, marine environments are ion soup, making it the ideal place for bacteria to proliferate, as such marine environments are extremely biologically complex. Especially when adding organic carbon, the bacteria proliferate quickly, and in some cases I think too quickly, resulting in bacterial blooms that reach critical mass, and then die, which results in a larger quantity of biomass being produced then that which was present before dosing, which then breaks down into nutrient.

By adding smaller quantities of bacteria, the nutrient is digested (and then removed by protein skimming) at a slower more "controlled" rate, resulting in better nutrient removal. Unlike freshwater systems, larger volumes of bacteria are needed because in a freshwater system organic carbon is not fuelling rapid reproduction of the bacteria being added, and therefore not only is more bacteria needed to break down the waste, but the bacteria added does not spike exponentially as there is a certain degree of biological control in that there is a limitation on the amount of organic carbon present to fuel biomass growth.

Some things to remember when choosing and dosing bacterial products are:

- not all bacterial supplements are created equally, you must research your chosen bacterial product and make your own findings, monitoring of water parameters and water quality are very important in this regard
- When dosing bacteria, oxygen can be depleted, ensure good aeration is provided and do not exceed manufacturers dose rates lightly, as I have said, some systems will need higher volumes of bacteria than others, but exceeding manufacturers dose rates should be done with caution, and slowly, whilst carefully monitoring water quality and oxygen levels.
- dosing bacterial supplements dose not reduce the need for water changes, it does in most cases improve water quality and reduce waste, but water changes do more than simply remove waste products from the aquarium, it replenishes salts and minerals, replenishes pH and removes the end products of bacterial reduction like staining and generally freshens up your water.
- in marine aquariums, in most cases, when dosing a bacterial supplement, you must have a protein skimmer, and unless you have a lot of experience with marine ecosystems and bacterial driven systems and dosing, I would not recommend even trying to run a bacterial system without a protein skimmer
- although heterotrophic bacteria can have long shelf lives owing to the fact that they can form spores or go dormant in liquid form, they are much better off being kept in the fridge. When looking for a bacterial product, one that recommends it being kept in the fridge (or is being kept in the fridge by the aquarium store) and has a range of dose rate information, but albeit is still very concentrated are things to look for that more often than not indicate a product that is worth trying.

Other advantages to dosing Bacterial Probiotics:

- the reduction of nitrate to nitrogen gas results in carbonates used up in the nitrogen cycle to be re-released back to the aquarium, providing a degree of "re-buffering" for the water, keeping your pH more stable.
- dosing bacterial products results in a process called competitive exclusion, by which bacteria out-compete disease causing bacteria resulting in a lower likelihood of fish contracting disease, and because most diseases are bacterial, or start off as bacterial disease, this reduces a vast percentage of chances of your fish catching disease. This, and the improvement in water quality overall, results in the fish having a better immune response, which results in much healthier fish tank inhabitants.
- Further to this, some bacterial supplements have have specific disease reducing bacteria that produce antibacterial/antimicrobial substances that directly harm/denature/kill other bacteria that can potentially cause disease.
- heterotrophic bacteria can in some cases perform ammonia and nitrite reduction as well, this is referred to as heterotrophic nitrification, and in general is not as effective or as long lived as autotrophic nitrification, but still is very beneficial.
- Probiotic waste assimilating bacteria remove the vast majority of solid waste (the good ones do anyway) which improve the nitrifiers ability to process ammonia and nitrite, this results in a faster functioning nitrogen cycle which means your tank can resist or cope with changes in ammonia levels faster, processing waste quicker. It also means solids wastes will be broken down faster into other compounds including ammonia, resulting in a tank that doesnt have as much chance of building up harmful by-products.
- heterotrophic bacteria in Probiotic bacterial supplements create biofilms, in these biofilms (and in the water column) solids wastes especially are broken down into "simpler" elements and "chopped" up into finer particles. Once this is done, the bacteria then microfloculate these small particles by incorporating them into their biofilm, these are then easier to collect by mechanical filtration.
- An interesting fact about bacteria and pre-filter sponges, in the course pre-filter sponge often included in cannister filters and other sorts of filters, a huge amount of bacteria is present. Most people will wash these off when they clean their denser, finer filter pad. Whilst you really have no option with the dense filter pad, the coarser, more open cell sponge can easily be squeezed out in water from the tank and be relatively well cleaned, this removes the solid waste but retains the bacteria. Sponges and media that are loaded with bacteria are "stickier" and will collect more waste as they collect micro fine particles in their biofilms.
- along these lines again, dosing pro-biotics will help keep you biofilter media cleaner, just like it keeps your substrate cleaner allowing for increased nitrification. However, there will still be a point where the biofilm on the outside of the media will get too thick and the hetertrophic bacteria will risk smothering the nitrifying bacteria already on the biofilter media. Every couple of weeks when you open your canister filter to check and clean the prefilter sponges, have a look at your biofilter media (noodles, bioballs etc) and if needed, give them a slosh in water from the tank to remove any mulm, you will find you will get a much better result with more regular maintainence.
----- On a side note, anyone who recommends a canister filter only needs to be pulled apart and looked at/cleaned every couple of months (and i have heard of people recommending only every 6 months) is completely incorrect. Even in a lightly stocked aquarium you would want to pull it apart and at least have a look at the impeller and give that a clean, and Activated carbon should be replaced every 3-4 weeks in a normally stocked aquarium anyway. Look at it this way, the more often you maintain your canister, the more waste you remove from your system on your pre-filter sponges, and this is waste that can break down into ammonia and other waste products in your aquarium. That, coupled with checking the impeller and checking for blockages means that the canister runs smoother and you should get a longer service life out of it.

So that's it really, at least that's all i can remember at 2am, if you have any questions or comments please feel free.

G