Silicate in aquarium water is considered rather unpopular among aquarists because it promotes algae growth. The mineral is primarily relevant in the start-up phase of a pool: Since the ecological balance in the water is established during this time, an increased silicate value together with increased algae formation is quite common. But what is silicate in the aquarium? When are values ​​too high – or too low? This article explains the background.

What is silicate in the aquarium?

The mineral silicate (alternatively: silicate) is an elementary component of nature. All planets similar to Earth contain high amounts of the silicic acid salt. The mantle and crust, for example, consist almost entirely (90 percent) of the mineral. What is silicate in the aquarium? First of all, the substance counts as an ester or salt for silicic acid. At the molecular level, it is composed of a silicon atom to which four oxygen atoms are attached. The chemical name is therefore SiO4.

The targeted use of these compounds happens practically in the treatment of drinking water. Because it prevents corrosion and deposits of lime in pipe systems. A mixture of phosphate and silicate primarily serves this purpose. This is important information for aquarists, because the water (and its quality) is essential for running in aquariums and regularly changing some of the water.

The silicate is dissolved in small amounts in the form of silicon dioxide (SiO2) in the aquarium water. It is relevant in both freshwater aquariums and saltwater tanks. In saltwater aquariums in particular, mussels, sponges and, last but not least, coral reefs need a certain amount of silicon compounds in order to form their respective framework. However, many aquarists consider high silicate levels to be a concern because of the formation of algae.

Causes of high silicate levels in the aquarium

How is silicate formed in the aquarium? The reasons for an excessive silicate measurement are easy to determine. The running-in phase in the aquarium leads to an ecological balance of the micro-bacteria. The silicon compounds are usually not a significant problem. However, can high levels in tap water also lead to increased silicate levels in the aquarium water.

In addition to tap water, silicate often ends up in the tank for other reasons. This happens for example the ground (Soil). The substrate is particularly important for aquascaping. Plant growth and nutrient distribution are fundamentally influenced by the material chosen.

Gravel and sand have so far been the usual means of shaping the bottom of the pool. Soil is a younger product in aquaristics. It is a nutrient-rich soil that, among other things, releases humic acids into the water and can reduce the water hardness. Due to the contained fertilization, more and more silicate gets into the aquarium water. The choice of plants and the more frequent water changes in the running-in phase is the same Soil breeding ground essential to prevent algal blooms.

Consequences of too high silicate levels in the tank

Diatoms / Jofre, Corydoras aeneus 1.0, marked as public domain, details on Wikimedia Commons

What are the effects of increased silicate levels? The consequence is increased amounts of diatoms and brown algae. Such coatings show up in the aquarium primarily as a slimy, flaky or brownish structure. Green algae often crowd out diatoms as soon as the composition of the microbiome changes further due to decomposition processes. As a rule, the algae problem solves itself in the run-in phase.

When to measure and combat silicate in the aquarium?

If unwanted algae are growing in the tank, it is worth checking the silicate levels. There are basically two ways to determine silicate in water. A cost-effective and time-saving method is to ask the public utility company about the silicate value in drinking water. In many cases, this information can also be found on the Stadtwerke website.

The second method consists in the independent measurement of silicate. The trade offers extra silicate tests for this. These are special solutions that color a water sample accordingly. This coloring can be compared with a separate color scale to determine the approximate silicate value. In addition to the usual standard water values ​​(e.g. degree of hardness, pH value, nitrate, nitrite, carbon), silicate values ​​are important for healthy plant growth in community tanks.

When is the silicate value too high in the aquarium? The measured values ​​for silicate in a freshwater aquarium are ideally below 2.0 mg/l. The value is harmless in the measuring range from 0 to 2 mg/l. Limit values ​​between 0.5 and 2 ppm apply to saltwater aquariums. If the water values ​​exceed or fall below this scale range, there is often a need for action.

Why fight silicate in the aquarium? Poorly growing plants and an insufficient supply of nutrients can be the result of high silicate levels. In order to create an optimal microbiome, it is worth checking the values ​​and taking an appropriate approach.

Avoid silicate in the aquarium – possibilities

An algae problem can be solved naturally algae eater remedy. Shrimp, snails and certain ornamental fish are known to kill algae. Among the ornamental fish, the following barbs and catfish are noteworthy as algae eaters:

• Siamese Algae Eaters (ideal for brush algae or filamentous algae)
• Ear lattice loricariid (diatoms, green algae)
• Antennae catfish (algae and other deposits)

Technically effective preparations such as «Silikat Ex» also help to reduce the amount of silicate in the water. Such additives are as silicate remover or silicate absorber common. Special filter materials also contain granules based on iron hydroxide. As a result, it binds silicates – and other nutrients. Also, since the material becomes saturated over time, it requires regular replacement. In principle, it is worth filtering the water separately before changing it in order to keep the silicate value low. An ion exchanger is also suitable for this.

Next to it is the osmosis with a reverse osmosis system a proven remedy against excessive water values. It demineralizes the fresh water. A full desalinator in the water (DI water) also supports the production of suitable replacement water. So-called hardening salt is suitable for the water hardness. Mineral salts generally help to achieve optimal water values. The entire process is complex, but osmosis ultimately enables precise influencing and control of the water values.

Conclusion – silicate in the aquarium

In the aquarium, silicate is largely undesirable. Tests and information from the local public utility company enable the reliable determination of silicon dioxide. Elevated silicate levels are reflected in increased algae growth. This can be observed primarily in the run-in phase. Anyone who later discovers problems caused by too much silicate in the aquarium can use algae eaters, osmosis, ion exchangers, demineralizers, silicate removers or silicate absorbers.