Snow in the tank: four clarifiers compared

In recent decades the management of reef aquariums has changed radically: from purely mechanical and biological filtration systems we have moved on to far more sophisticated physico-chemical approaches. At the centre of this shift are the products called "snow" and mineral concentrates with a high active surface.

At first sight they look alike: suspensions or powders that cloud the water and then clear it. In reality their biochemical basis, how they act and their ecological aims are profoundly different. In this article we look at ATI Easyvital, Korallen-Zucht Coral Snow, Modern Reef BIOReef-Snow and Resolve, to understand the differences and the best use of each.

Water clarity and colloidal systems

In a closed environment such as a marine aquarium, water quality is constantly degraded by the build-up of dissolved organic substances (DOM), phenols, humic acids and other metabolites that turn it yellow. It is not just a question of looks: these substances act as biological inhibitors, reduce light penetration and hold back coral growth.

Many of these pollutants are colloids: tiny particles with a negative electrical charge, which stops them from clumping together and from being removed by normal mechanical filtration.

The products we are looking at act on this balance through three processes:

• adsorption, a physical process in which contaminants stick to the surface of an adsorbent material (clays, activated carbon) without entering its structure;
• ion exchange;
• flocculation, which neutralises the charges of the colloids and lets them join into "flakes" big enough to be removed by skimming or mechanical filtration.

1. 1Adsorption the dirt sticks to the surface of a particle (clay, carbon) without getting inside it
2. 2Flocculation the colloids' charge is neutralised and they join into flakes big enough to end up in the skimmer
3. 3Skimmer removes dirt-laden particles and flakes from the water

The mineral grabs the dirt, the flocculant clumps it together: then the skimmer takes over.

Adsorption and flocculation.

ATI Easyvital: active clay minerals

ATI Easyvital is a product based on a highly active natural clay mineral, as a fine powder. Unlike liquid facilitators, it exploits the properties of phyllosilicates to purify the water by purely physical and chemical means.

Mineralogy and specific surface area: the main component is a clay mineral with a very high specific surface area. These structures are made of layers of silica tetrahedra and alumina octahedra, which create micro-cavities and channels able to trap organic molecules and ions. The particles measure about 2 µm: small enough to stay suspended long enough to act, before being removed by the skimmer.

Detoxification and ion exchange: thanks to its surface charge and porous structure it binds heavy metals such as copper, zinc and cadmium, as well as drug residues and chlorine. A crucial aspect is its ability to bind ammonium and ammonia, in a similar way to zeolites but directly in the water column. By removing ammonium before it enters nitrification, it reduces the formation of nitrites and nitrates and helps prevent unwanted algae.

In short: natural powder · active clay mineral · particles of about 2 µm · physical adsorption and ion exchange · binds ammonium early · 100% natural, harmless even if overdosed.

Effects on the tank and the corals: fewer biological inhibitors means more extended polyps and better growth. Removing phenols and colouring substances improves clarity and so lets more light through; reducing the bacterial load in the water helps prevent infections.

Korallen-Zucht Coral Snow: the biological facilitator

Coral Snow is a pillar of the Zeovit system and represents a different approach: it is not just a clarifier, but is described as a "secondary biological facilitator" for nutrients and bacteria.

Composition: it is a liquid suspension with a natural mix of calcium and magnesium carbonates, with particles of about 2.5 µm, designed to be easily taken up by SPS and removed by the skimmer. A distinctive function is neutralising unwanted acids and yellowish compounds that activated carbon cannot catch. Even though it contains carbonates, it should not be considered a calcium or magnesium supplement: its function is purely reactive in the water column.

Biological facilitation: its most innovative feature is its ability to boost the effect of other KZ products such as Amino Acids, Coral Vitalizer, B-Balance and Potassium-Iodide/Fluoride Concentrate (the famous recipes). By mixing Coral Snow with these additives and leaving it to stand for 5 minutes before dosing, the carbonate particles act as carriers: they concentrate the nutrient molecules on their surface and make them easier to catch for corals that feed on fine particles, imitating natural marine snow.

In short: milky liquid suspension · calcium and magnesium carbonate · 2.5 µm particles · facilitator for nutrients and bacteria · pairs with amino acids, Vitalizer, B-Balance, ZEObak · also used against cyanobacteria and algal films.

Cyanobacteria and stability: Coral Snow is widely used against cyanobacteria, adding one drop of ZEObak per 100 litres (purely indicative doses) to the dose of Coral Snow. In this combination the "snow" becomes a colonisation site for beneficial bacteria, which arrive straight on the surfaces where the cyano grow. Competition for space and nutrients helps get rid of them naturally, without antibiotics or harsh substances.

Modern Reef BIOReef-Snow: flocculation and vitalisation

BIOReef-Snow is a further development of the "snow" idea: it combines flocculants with biological stimulants for filter-feeding organisms.

Flocculation and toxins: unlike clay-only or carbonate-only products, it is described as a mix of different flocculating compounds. Flocculation is more active than adsorption: it neutralises the colloids' charges and forces them to clump together. It is formulated to bind organic pollutants, ammonia, phenols, humic substances and the "stinging poisons" corals release in their chemical war for space. The flakes are then removed by the skimmer and mechanical filtration.

Support for sponges and tunicates: a distinctive feature is the "sponge vitalisers". Sponges and sea squirts are a vital part of the reef's natural filtration: they process enormous amounts of water and remove bacteria and dissolved organic carbon (the sponge loop). BIOReef-Snow encourages their growth and so their ability to clean the water.

1. 1Dissolved organic matter dissolved organic carbon in reef water
2. 2The sponge filters huge amounts of water and takes up the dissolved matter
3. 3Detritus the sponge quickly sheds its filter cells
4. 4Reef fauna eats the detritus: the carbon stays on the reef

Sponges turn dissolved dirt into food for the reef.

Sources: [1]

In short: mix of flocculants · sponge vitaliser · acts on ammonia, phenols and coral poisons · used against dinoflagellates, cyanobacteria and algal films · support for BIOActivator and BIOBac · crystal-clear water and fewer bad smells.

The protocol against dinoflagellates and cyanobacteria: BIOReef-Snow is part of the Modern Reef protocol, which aims not only at physical removal but at creating an environment that favours beneficial microorganisms. It is mixed with BIOBac (full-spectrum bacteria), BIODiversity (for microfauna) and BIOActivator (an enzyme-based stimulant); the mix stands for 4 to 12 hours and is dosed with the lights off, to maximise biological competition.

Resolve: multi-mineral purification

Resolve is an "all in one" solution that combines several classes of purifying materials in a single colloidal suspension, exploiting the synergy between different minerals for a shock action.

Composition: a mix of carbonates, zeolites, clays and other micronised minerals. It looks like a milky liquid and goes into suspension straight away: it binds to unwanted organic molecules and contaminants, which filters and the skimmer can then remove.

Cyanobacteria and heavy metals: it is particularly effective against cyanobacteria and bacterial clumps, helping them aggregate and so be exported mechanically. It is also very effective at removing dissolved heavy metals.

Benefits for stability: besides purifying, it encourages the growth of coralline algae, contributes to the stability of pH and KH and, by removing organic inhibitors, gives corals a clean, balanced environment.

In short: milky colloidal suspension · carbonates, zeolites, clays and micronised minerals · cyanobacteria, bacterial films and heavy metals · stability of pH and KH, growth of coralline algae.

The differences in short

Clay minerals (ATI Easyvital): they excel at ion exchange and binding ammonium. Ideal for stabilising new systems or handling inorganic spikes.

Carbonates (KZ Coral Snow): they act as a "shuttle" (carrier) for nutrients and bacteria and neutralise weak organic acids.

Flocculants and vitalisers (MR BIOReef-Snow): they force complex organic toxins to aggregate and support the "cryptic" biological filtration of sponges.

Multi-mineral complex (Resolve): an all-round approach that combines the adsorption of clays and zeolites with the stability of carbonates. Specific for removing bacterial films and metals.

ATI Easyvital

• Active clay · ~2 µm
• Binds ammonium and heavy metals
• For new systems or inorganic spikes

KZ Coral Snow

• Carbonates · ~2.5 µm
• Acts as a "shuttle" for amino acids and bacteria
• The heart of Zeovit

MR BIOReef-Snow

• Flocculants + vitaliser
• Toxins, coral poisons and dinoflagellates
• Helps sponges

Resolve

• Multi-mineral mix
• Shock action on cyanobacteria, films and metals

There is no single one, and no best one.

Four products, four jobs. Descriptions based on what the manufacturers state.

Cyanobacteria and dinoflagellates

Coral Snow and Resolve against cyanobacteria: Coral Snow is traditionally used as a carrier for ZEObak, to create bacterial competition. Resolve takes a more "physical" approach: the micronised mix attacks the clumps and films, helping them detach and be removed by the skimmer or filter floss.

BIOReef-Snow against dinoflagellates: dinoflagellates are one of the hardest challenges in modern reefkeeping. BIOReef-Snow is offered as a solution against them, as well as against cyanobacteria and algal films: it binds the toxins they release (often lethal to snails and other invertebrates) and supports a microbial web able to compete for resources. Together with BIOActivator and a temporary "blackout" it forms a complete protocol.

Easyvital and preventing infections: ATI's approach aims to reduce the free pathogenic bacterial load in the water. By reducing the germs and the nutrients harmful bacteria feed on, it creates an environment where infections are less likely. It suits preventive maintenance and systems showing general stress without a clear cause.

The role of the skimmer

All these products depend on the skimmer to finish the job. On its own the skimmer cannot remove very small organic molecules or dissolved ammonium: clarifiers get round this limit by "loading" these substances onto mineral particles (adsorption) or by clumping them together (flocculation), suddenly making them skimmable.

With Resolve and BIOReef-Snow in particular, in the days after dosing you may need to clean the pre-filters and the skimmer cup more often, because of the amount of material removed.

Which one to choose?

If you have read this far, you will have realised by yourself that there is no single one and no best one!

When to choose ATI Easyvital: if your main goal is pure physico-chemical purification and stabilising inorganic nutrients. It is the ideal product for those who prefer a "100% natural" approach based on clays: it removes heavy metals, ammonium and chemical residues cheaply and safely. Being a powder, it can be dosed precisely by weight.

When to choose KZ Coral Snow: if you follow the Zeovit method or want a facilitator for coral nutrition. It is unbeatable with amino acids and bacteria (ZEObak) for handling cyanobacteria and improving the general health of SPS: a system proven over decades for extreme colours and "show" water. If you also have a phosphate problem, the Coral Snow Plus version offers a combined solution.

When to choose MR BIOReef-Snow: if you are facing complex problems such as dinoflagellates or want to focus on advanced biological filtration (sponges). Its flocculation is more powerful on complex organic toxins and coral poisons. It is the best suited to modern aquariums that use "synthetic" microbiology and are after very clear water without smells.

When to choose Resolve: for shock action against cyanobacteria and bacterial films. It is the best option for those who want broad-spectrum multi-mineral purification that removes heavy metals and toxins while stabilising pH and favouring corals and coralline algae.

Who wrote this article

Sources

1. de Goeij J.M., van Oevelen D., Vermeij M.J. et al. (2013). Surviving in a marine desert: the sponge loop retains resources within coral reefs. Science 342(6154): 108-110.