How to Remove Silica From Water

How to Remove Silica From Water

Silica is a contaminant that can be found in water. It is a compound of silicon and oxygen, and it is found in sand, quartz, sandstone, granite, and the skeletal remains of different plants and animals.

All natural water does have some dissolved silica in it, and some water has colloidal silica. It is also found in a number of different foods, including cucumbers, avocados, root vegetables, and more.

The earth’s crust contains 80% to 90% silicates and compounds of silica, so water collects it from sand, rocks, or minerals as it travels. The silicates are categorized as salts, and they are found in a number of minerals, such as mica, asbestos, talc, lava, and more.

Silica colloids are tiny particles in the water, and they are thought to have a negative charge, so they repel each other and never become a larger solid. They remain suspended in the water.

It is important to remove the silica from water because it can form deposits. There are different methods for removing silica, but the first step is to test your water.

Standard Test Method for Silica in Water

The standard test method is a colorimetric method, and it determines the molybdate-reactive silica. It can be applied to most waters, and it has shown success with concentrations as low as 20 [u]g/L.

It will show the photometric determination of the molybdate-reactive silica in water, which includes simple dissolved silicates, monomeric silica, and silicic acid.

The best way to do this is through a lab.

Methods of Silica Removal From Water

There are different methods to remove silica from water, and the process varies depending on whether the goal is to remove dissolved silica or colloidal silica.

Dissolved silica responds well to reverse osmosis, while colloidal silica does well with ultrafiltration.

Once water is tested by a lab, it is much easier to know which type or removal method will be most effective.


Ultrafiltration is cost-effective and low maintenance, but it will only reduce colloidal silica.

It uses a UF membrane to separate colloidal silica from water. It is highly efficient, and it takes up less space than other systems.

Reverse Osmosis

Crystal Quest CQE-IN-00309 Voyager Triple Inline Water Filter For Fountains and Coolers with Ultrafiltration

When reactive silica is present, reverse osmosis (RO) works the best, especially in a residential environment.

The RO membrane has very tight filtration, so it is able to separate the silica from the water. RO is capable of reducing both reactive and colloidal silica.


Ion Exchange

Because silica molecules carry a negative charge, they need an anion resin to reduce them.

In ion exchange systems, the resin needs to undergo regeneration with a caustic soda (NaOH) solution. The silica molecules will exchange with the hydroxide (OH) ions.

The pH of the water will be higher than with other types of resin, so pH reduction is often required after the silica reduction.

Chemical Precipitation

This process forms a separable solid substance from a solution, and it can be done by converting the silica into an insoluble form or changing the composition.

It can be used successfully with some colloidal and dissolved silicates.

How to Remove Silica From Drinking Water

The first step is to have a test done on the water. It is important to determine whether there are colloidal and dissolved silica.

Once the results are back, it is much easier to determine what needs to be done to remove silica from the water.

There are several different processes you can use to remove silica from water, depending on how much silica is in the water.

An ion exchange can remove silica as long as it has the correct resin base.

Reverse osmosis is very successful at removing silica because its tight membrane is separated from the water. It can remove 85% to 95% of the silica from drinking water.

Finally, if there is silica in colloidal form, it may require ultrafiltration because it would be too harsh on the RO membrane.

Reverse osmosis removes silica by using water pressure to force the molecules of water through a semipermeable membrane.

As the water molecules hit the membrane, the silica is separated and does not enter the water system. The silica that is separated is flushed through a drain.

How to Remove Silica From Aquarium Water

How to Remove Silica From Aquarium Water

When you find brown algae in your aquarium, it is caused by single cell organisms called diatoms. They are able to join together and grow because they feed on silicates in water.

As they grow and join together, the water in the aquarium will turn a rusty-brown color. The silicates can come from the tap water, and it is necessary to remove them.

First, it is important to clear silica from the glass. This can be done by using a cloth or sponge to wipe the glass. Then, you should remove it from the gravel. You can remove the gravel and wash it, using a filter to let the silica fall away.

You can add organisms that eat silica, such as Nerite Snails, Amano Shrimp, or Mexican Turbo Snails.

Most of the time, silica can be controlled with proper filtration. You should ensure that the filter is the right size for your tank, and make sure that you clean it regularly.

Changing the water once a week will also help, and if you have an RO system to filter the water in your home, it will help to ensure that less silica gets into the tank.

Increasing the flow of water in your tank will also reduce the growth of silica.

The bottom line is that using an effective filter system for your aquarium, cleaning it regularly, and filling your tank with water treated by RO will help to prevent silica growth in your aquarium.

How to Remove Silica From Boiler Water

Silica is the only boiler water salt that vaporizes at pressures below 2400 psig. As a result, it can cause problems with deposits being formed as well as scaling.

It is important to control the external water source so that this damage is minimized, as can be done through an RO system, ultrafiltration, or ion exchange.

Once the silica has entered the boiler system, one way of dealing with it is to increase the boiler blowdown.

You can also have a cleaning done by blasting the boiler with aluminum oxide or another material to remove the deposits.

How to Remove Silica Stains

If you have silica in your water, you will find stains that are left behind after the water dries. It looks like a white substance on your toilet, sink, or shower doors.

Fortunately, it is not too difficult to remove it, and there are several different products and substances you can use.

Baking soda will help to remove stains and whiten surfaces. If you have a spray bottle, you can mix baking soda with hot water.

Use one to two teaspoons of baking soda in this solution. Spray the area where you see silica buildup, and scrub it with an old toothbrush until it is gone.

If you need a stronger mixture to remove the stains, you can buy a hard water deposit remover from the hardware store. It will help remove other mineral build up as well.

You can also try vinegar. If you mix vinegar with water, you can spray silica stains. Let it sit for a few minutes, and then scrub it away.

Fortunately, silica is not terribly difficult to remove as long as you have one of these products.

Frequently Asked Questions

1. Is it possible to install a whole house reverse osmosis system to remove silica?

Yes, but it is expensive (price $12,000 to 18,000). The cost of installing a whole house reverse osmosis system depends on several factors, but it is most closely related to the amount of water that needs to be generated per day.

Another factor that affects the cost is the amount of pre-filtration equipment required. You would need a larger system if your water demand is higher than the average household.

The installation cost plus operating cost of the reverse osmosis system are also linked to the frequency of membrane and pre-filter replacements.

Additionally, the majority of whole home reverse osmosis systems remove contaminants that are flushed down the drain, which can drive high water bills.

2. Will a reverse osmosis system remove both colloidal and reactive silica?

Yes, it can effectively remove both.

3. Is silica in drinking water harmful?

Silica is not considered to be harmful in drinking water, and some researchers suggest that it is able to decrease the potential impact of aluminum in water.

Final Words

Silica is one of the most common compounds found in the earth’s crust, and as a result, it is found in most water. As with other contaminants, it is important to test your water to determine how much silica is in the water, as well as its form.

Once you know whether you have dissolved silica, colloidal silica, or a combination of the two, you can determine the best system for removing the silica from your water.

There are different methods of removing silica from water, but Reverse Osmosis (RO) seems to be effective at removing both forms.

If there is an extraordinary amount of colloidal silica, you may need to use ultrafiltration to eliminate some of it, but as long as you keep your reverse RO clean, RO can do the trick most of the time.

When it comes to removing stains left behind by silica, you have different options. Baking soda, vinegar, or a special product available at hardware stores will do the trick.

Jon Agarwal

Jon Agarwal works as an environmental consultant focused on water resources, and he volunteers his time for non-profit organizations. He lives in the heart of Melbourne with his beautiful wife, two sons, and three Persian cats. He particularly enjoys working part-time as it leaves him the time to work on his own writing and share his knowledge. Visit our About page to learn about the contributors of Healthy Buddys.

You may also like...

Leave a Reply

Your email address will not be published. Required fields are marked *