Phytoplankton FAQ: Let's clear up some doubts!

Essential guide to frequently asked questions about the use, cultivation and benefits of phytoplankton in aquarium keeping.

In your fertilizer you claim to use a proprietary formula, but I recently discovered that according to the FAO (Food and Agriculture Organization) protocol there are only two types of fertilizer, and variations of the recipes are not possible. Who is right?

As previously explained, the basis for the development of our fertilizer is the desire to offer an innovative product, to bridge the gap between the needs of mass cultivation of microalgae in industrial aquaculture and those of reef aquariums.

Let's start by saying that there is no FAO protocol.

The manual that is probably mistakenly referred to is the “Manual on the Production and Use of Live Food for Aquaculture” or “Guide To The Production Of Live Food Organisms”.

Despite their completeness and the quality of their information, these are two documents (from 1994 and 1988 respectively) entirely dedicated to the development of aquaculture in emerging countries.

They are an excellent basis for understanding the fundamentals of phyto and zooplankton farming, but they remain decidedly dated texts and of a level that I would define as inadequate for our sector.

However, it is enough to browse both to immediately notice the inconsistency of this statement. Precisely because they are dedicated to the training of technicians in developing countries, they also teach the use of agricultural fertilizers and manure, with a good ten different recipes, clear data.

We are posting the links because they are excellent manuals for those who want to start experimenting with phyto and zooplankton cultivation.

https://www.fao.org/3/w3732e/w3732e06.htm#2.3.%20Algal%20production

https://www.fao.org/3/ab880e/ab880e00.htm

From what I've read, silicates are also essential for growing microalgae.
It is true?

Although many potentially harmful microelements (especially when in excess) are essential for the correct development of algal cultures, the addition of silicates is useful (and in that case absolutely essential) only if you are growing diatoms.


The frequent presence of high levels of silicates (and generally metals such as Zinc and Copper ) within crops is also due to the fact that inadequate and undeveloped media for the sector are still used for cultivation.

I grow my own Synecho mix, usually letting the cells settle to the bottom and only using the “concentrate” part.

I always reuse the remaining water for subsequent crops. Am I doing the right thing?

No, it is not recommended, mainly for two reasons:

You deprive yourself of all those dissolved bioactive molecules produced by algae (chemical warfare and competition between microalgae, antimicrobials and antivirals, exopolysaccharides, etc.).

Reusing the same growing water causes imbalances and accumulations of unabsorbed ions, especially when using fertilizers that are unsuitable for the purpose.

If you do not use an adequate fertilizer or do not respect the correct suspension and harvest times, it is typical to find residues of copper, zinc , silicates and any other ion that has not been absorbed by the cells and transformed into algal biomass.

Furthermore, the accumulation of algal catabolites and bacterial contamination generally cause slowdowns in production and bacterial imbalances, both in culture and in dosing in the system. If you have been dosing cultivated phytoplankton in the same water for a long time, we recommend performing an ICP in the tank to look for metal contaminants.

They told me that the live phyto dies in the tank and is of no use, that the concentrated phyto is better.

It is true?

We find it incomprehensible and reactionary to persist, for twenty years, in a crusade against microalgae, despite the fact that their use and potential is now well known and widely recognized.

The purpose of dosing live phytoplankton goes far beyond its nutritional function, it is a fact that is now well-established and widely verifiable.

Very often its dosage is recommended with the aim of rebalancing an unbalanced system, as an adjuvant during a treatment, or to fight against algal/bacterial proliferation.

Its use in larval weaning with the green water technique has allowed major advances in both the aquaculture and aquarium sectors.

To answer the question, it depends on what purpose you want to use it for, they are two totally different products.

If your goal is purely nutritional, if you want to “fine tune” by increasing phosphates or if you simply want to dirty the system, concentrates are much more effective.

If the goal is to balance and provide support to the system, increase biodiversity, competition and biological control, live cultures (not chemically or mechanically treated) are by far the best choice.

Why don't you ever talk about Spirulina? And Nanno?

As for Nannochloropsis, although it has a role in professional aquaculture, if we don't talk about it (and don't grow it) it is for various reasons but mainly because:

• We do not consider it (from a nutritional point of view) comparable to the many other cultivable species.
• The size of the cells is really too small.
• It resists even in the presence of contaminants, excess nutrients or inadequate cultivation parameters.

Its excessive stability (and simplicity) of cultivation means that it very often results in a poor quality product.

As regards Spirulina , whose role in aquaculture is extremely marginal and is reduced almost exclusively to its simple presence as an ingredient in food, the basic problems are the same: contaminants, stability, organoleptic qualities, size (excessively large for the vast majority of target organisms) .

Added to this is the fact that it is a freshwater species and does not colonize the system at all , contrary to what is often said. If we consider the (rare) saltwater species, colonization of the system is absolutely not desirable, most of them create panniculi extremely similar to the classic cyanobacteria that we all know.

In short, here too we prefer to dedicate our attention to more innovative and promising species.

Is it true that the phyto concentrate remains alive?

It depends, there are many different techniques for the concentration of phytoplankton. There are some “mild” techniques, which allow to keep the cells intact and vital, without damaging them.

Among the less aggressive concentration techniques we can mention sedimentation (the most natural and gentle for the cells, but also the longest and least efficient), flocculation and flotation (unfortunately flocculants and flotants are often relatively harmful chemical products) and finally membrane ultrafiltration.

Unfortunately, however, their efficiency is extremely limited and generally techniques more suited to industrial needs are preferred.

On the contrary, centrifugation , freeze-drying and spray drying are extremely high-performance techniques and are therefore selected by the industry, but in the vast majority of cases they irreparably damage the cells, making the product useful exclusively from a nutritional point of view.

To cut it short and answer the question without needing excessive reflection: to verify the actual vitality of the cells of any concentrate, it is sufficient to put them back into culture in the correct conditions and verify their growth.

Can phyto dosing be automated?

It depends here too.

In the case of concentrated products in liquid suspension, the conservation technique or the preservatives contained in the mixture are generally sufficient to maintain the product in a sufficient state of conservation, however we always recommend relying on products developed for the purpose.

In the case of live phytoplankton, however, contamination of the culture and unwanted proliferation inside the pipes is much more frequent, so we do not recommend connecting it directly to the reactor .

In both cases, dosing can be automated, provided that good hygiene practices are respected by regularly sterilizing tubes and vessels, and adequate technical measures are put in place.

For example, the use of valves and timers for rinsing the tube, magnetic stirrers to keep the cells in suspension, or small dedicated refrigerated systems can be evaluated.

Is it true that phyto should not be kept in the fridge?

No, phytoplankton is stored in the refrigerator precisely to keep the cells viable for longer. This method is commonly used both in the laboratory and for practical applications, as it slows down the metabolic processes of the cells, prolonging their viability .

Storage at low temperatures (typically between 4 and 8 °C) is ideal for medium to long periods of time, generally up to a few months , depending on the phytoplankton species and specific storage conditions.

I've been told that even in the fridge it doesn't last more than 2 or 3 weeks.

It is true?

We kept mother cultures in the fridge for 6 months without shaking , once put into culture they all restarted without any problem.

With the right precautions they can be stored in the refrigerator for much longer periods.

For freezing, however, cryoprotectant agents (such as glycerol or dimethyl sulfoxide, DMSO) are needed to protect the cells during freezing, suitable containers for the sample (e.g. cryovials), and liquid nitrogen for rapid freezing and storage at extremely low temperatures (-196 °C).

It is important to optimize the concentration of the cryoprotectant and the rate of cooling to maximize cell survival after thawing.

These are not treatments that can be performed without the aid of extremely expensive laboratory equipment ; normally, it involves a very simple freezing, which however does not allow the cells to remain vital.

I opened the phyto stored in the fridge and it had a sulfur smell. Should I throw it away?

No , if all the cells return to suspension and no significant amount of debris is observed, a change in the odor of the phytoplankton is generally not serious and does not necessarily indicate that the culture should be thrown away .

Not all microalgae have a pleasant smell when cultivated or preserved; in fact, many of them are characterized by the presence of odors that some may find decidedly unpleasant.

Depending on the species, type of crop, stage of growth, additives present and storage method, the smell of a crop can vary greatly .

Furthermore, the natural and gradual degradation of animal and vegetable proteins causes the production of small quantities of hydrogen sulphide .

Our high sensitivity to the molecule and extremely low olfactory threshold means that the characteristic smell of sulfur can be perceived, even in the presence of very low and absolutely harmless concentrations of gas.

This natural process should not cause concern, it is a clear sign that the culture is alive and that no bacteriostatics, preservatives or chemical substances capable of interrupting these natural processes have been used .

My phyto has a strange color, how can I tell if it's alive?

To understand if a culture is still usable, simply shake it vigorously and then hold it up to the light: the culture must be clean, there must not be an excessive quantity of debris and solid particles, the cells must all return to suspension and the culture must regain a nice intense color .

The cells must remain in suspension for a long enough time, although some species tend to settle quickly, it is always a matter of a few minutes.

If after 5 minutes the water is crystal clear and the cells are all deposited on the bottom as gelatinous or powdery agglomerates, the product has lost its effectiveness and can be disposed of.

In the case of crops produced by companies in the sector, do not rely on colour at all, it is too variable a parameter to be considered as an indicator of the vitality of a crop.

Different species may have different colorations, but spectacular variations can also be observed within the same species.

Depending on the conditions and the cultivation technique, the density of the cells, the stage of development, the suspension times, the colour of the same culture can go from bottle green, to straw yellow, to an intense red.

The case of domestic crops is different, where we have often seen straw-yellow Nanno crops with an evident nitrogen deficiency sold as T-ISO, or as “white phytoplankton”, crops that have completely crashed in a bacterial explosion .

I invite you to verify the validity of “strange” statements by reading popular science texts and comparing yourself with the community.

Is it possible to overdose on phyto?

No. It's virtually impossible.

It is a living product and remains viable once introduced into the system.

This means that it does not pollute like a concentrate would and it maintains its activity until it is removed by skimming or retained by a filter organism.

The case of tanks that have just been set up with synthetic materials and absolute sterility is different ; in that case, unless the goal is to start the system with the green water technique, it is not advisable to introduce too much phytoplankton at once .

The system does not yet have a sufficient population to consume it entirely and if you introduce a particularly strong strain you risk having a persistent clouding of the water, similar to a bacterial bloom.

If a phytoplankton bloom occurs in the tank, it is sufficient to turn on the UV lamp for a few days , a device that we strongly recommend every enthusiast to own, so that it can be used when necessary.

Even a wet skim can help.

Skimmer on or off? Is it better to dose during the day or at night?

Skimmer off (even for an hour if possible).

For dosage, it can be administered when the lights are turned off to favor use as food or when the lights are turned on to facilitate the export of nutrients, chemical warfare and competition with other algae .

Can it be dosed together with other products? Which ones can't?

There are no dosage contraindications with any of our products and can be used as a base in the preparation of food mixes.

However, we do not recommend dosing it together with flocculants such as BEA Resolve, which would reduce its effectiveness and persistence in suspension.

In that case it is preferable to wait until the resolve has finished its action and the water is crystal clear again.

What is the point of alternating the dosage of the various strains?

Different strains of phyto have different functional, metabolic and nutritional characteristics .

Varying the strains introduced as much as possible helps the entire system on several levels: a high biodiversity guarantees better effectiveness in metabolic competition and chemical warfare , a greater variety in the size of the cells and therefore of the organisms that will feed on them, a greater synergy between the bioactive molecules introduced.

As for administration, the different products can be administered either on alternate days or at the same time, mixing them.

As for dosages, we always recommend adjusting them based on the tank: if we want to dose multiple strains at the same time, we recommend starting with the total quantity relating to the dosage of a single strain, then gradually increasing up to the total dosage.

For example, if we wanted to dose green, synecho, black and red in a 200 litre tank, we have two solutions, different depending on the metabolism of the system .

• In a young tank or one with a slow metabolism we will dose 200 ml of the different strains alternating them daily or mixing 50 ml of each of the 4 strains.

• In a tank with a high metabolism, we can gradually increase the dosage of the different strains, up to the absorption limit of the system.