Excess silicates can quickly become a hobbyist’s nightmare in both newly cycled and established tanks.
It can lead to an outbreak of silica algae or brown algae, which will hurt the aquarium’s ecosystem.
Silicates can leach into your tank from many sources.
Read on to find out what they are and how to reduce their levels.
How to Remove Silicates From Aquarium Water
Although you’ll never be able to remove all the silicate and silicic acid from the water, you need to keep the levels under control.
Anything over 0.5 ppm will cause problems.
Here’s what you can do.
1. Cut Out the Source
The most effective approach is to prevent silicate from getting into your tank in the first place.
Removing it can be much more demanding and costly.
- Tap Water – Your local tap water may contain high levels of silicates. That may be because of the natural source of water. For instance, many rivers contain excessive dissolved silicates. Additionally, sometimes water refineries add silicate compounds to the water to eliminate copper and lead leaching into the water from the pipes and raise the pH. Since silicates aren’t a threat to human health, there’s no regulation on removing them from tap water.
- Substrate – Your substrate should consist of quartz, a beneficial rock known for its low solubility level. Pure quartz is completely white. However, most commercial quartz or silica sand in the market isn’t close to being white. Most manufacturers claim that their silica sand contains 98% quartz. Even if that were true, what makes up the remaining 2%? They’re different minerals that can easily dissolve and leach unwanted compounds into the water. The truth is the sand you purchase doesn’t come from the beach. The minerals of the beach sand are either washed away or trapped inside the particles. Commercial sand comes from mining sand pits, and it contains excess minerals. Therefore, it’s best to choose the substrate wisely before setting up your tank. Once the tank is established, and the beneficial bacteria set sail in the substrate, removing it can mess up the nitrogen cycle.
- Salt – The salt mixes you add to your marine aquarium may be the source of the silicates. Let me remind you that you mustn’t add table salt to the aquarium because it can leach silicates and iodine to the water. Even some aquarium salt mixes that claim to be silicate-free contain some. Make sure you buy high-quality salt mixes to prevent this problem from happening.
- Other Sources – Other supplements that you add to your reef or saltwater tank may also be the culprit. Check the calcium and alkalinity additives for silicates. Limewater and fish food can contain silicates, as well.
2. RODI Units
Some hobbyists believe that installing RODI units is the best way to eliminate excess minerals, including silicates, from tap water.
What’s more, most RODI unit manufacturers claim their devices remove silicates from the water altogether.
Here is a video on how to choose a RODI unit.
On the other hand, other hobbyists argue that these units can only filter out silicates for a very short time.
According to them, these compounds can escape through the membrane in a matter of days.
Well, the best way to make sure is to test the filtered water for silicates.
You can also purchase readily made RO water from fish stores and test them for the compounds.
If they do work, performing water changes with RO water will solve your problem quickly.
3. Silicate Removing Compounds
Silicate removing compounds and silicate absorbing resins are your next best choice.
Here is a highly recommended product.
- Phosphate remover
- Rapidly removes phosphate and silicate
- For marine and freshwater use
Put them somewhere in the tank with sufficient water flow.
It could be in the filter, sump, or any spot that ensures the water comes into maximum contact with the material.
These compounds won’t last forever.
As soon as you notice any signs of brown algae in your tank, change the silicate removing material.
Your best chance of removing most of the silicate fast is by using products that only remove silicates!
Some multi-purpose compounds can remove phosphates and other minerals as well.
They may work just fine, but it’s best not to take the chance in emergencies.
Pre-treating the water with these compounds can be very helpful, too.
You’ll need a sieve and two buckets.
Put the sieve on one bucket and fill it with the silicate removing compounds.
Fill the other bucket with water and pour it on top of the sieve.
Repeat five times or more.
Once you’ve filtered more than 75 gallons of water, change the compound for a new batch.
4. Protein Skimmer
A protein skimmer is a mechanical filter which helps your primary filtration system remove organic compounds from the water before they get a chance to break down and release ammonia.
It removes uneaten food, waste, and toxins, increases the dissolved oxygen levels, and improves the water quality.
Experienced aquarists say it only removes 50% of the silicate compounds.
Nevertheless, having one will help take some of the weight off your shoulders and speed up the process.
How to Remove Silica or Brown Algae from Water
1. Eliminate the Silicate, Phosphate, and Nitrate
As mentioned, brown algae and diatoms need to consume phosphate and nitrates as well as silicates to grow.
Phosphate leaches into the tank from decaying fish food, plants, waste, or dead fish.
Sometimes, pH buffers or slat mixes are to blame for a rise in phosphate levels.
Using RODI units, protein skimmers, and media reactors with GFO can help reduce phosphate levels.
There are phosphate removing compounds, sponges, and pads commercially available.
Having a refugium with macroalgae can also help reduce phosphate levels.
The presence of nitrates means that your tank is cycling correctly.
It’s the natural by-product of the nitrogen cycle.
However, the excess amounts can cause problems and fuel algae growth.
Potential nitrate sources include tap water, fish food, decaying matter, plant fertilizers, and fish feces.
To remove nitrate, stick to a tight schedule of partial water changes.
2. Removing Silica from Glass
Using a piece of cloth or scrubbing pad, clean the aquarium glass.
Start from the top and clean the glass to the bottom by putting pressure on the pad.
Don’t move the pad up and down.
You should do this in a single motion, or else the algae bits will float in the water and set sail somewhere else in the tank.
3. Removing Silica from the Substrate
The easiest way of removing brown algae from gravel is by vacuuming it.
When you push the hose deep into the gravel, the bits will tumble around, and the detached algae bits will get sucked into the vacuum cleaner.
You can also remove the gravel from the tank and wash it with water, but that’s not recommended since it can hurt the beneficial bacteria.
Removing silica from a sand bed can be more challenging because the sand particles can easily get sucked into the vacuum cleaner.
First, you need to hold the vacuum hose above the sand to collect fish waste and uneaten food particles.
Then pinch the vacuum hose to reduce the suction power.
Stir up the sand with the hose to break down the silica and make it float in the water.
Un-pinch the hose and collect the brown algae by waving the hose above the sand surface.
4. Removing Silica from Plants and Decoration
Removing brown algae from the surface of corals and living plants is a must because the algae can block the light and not let the plant photosynthesize.
Get a water pipe with a hose.
Pour water on the coral and plants, so the silica comes off and gets trapped in the filter.
If the plants are strong enough, use a clean cloth to wipe off their leaves.
The best way to remove silica from fake plants and decorations is to get them out of the tank and wipe off the surface with a cloth.
In severe cases, use a bleach solution to get off the stubborn algae.
5. Turn Silica into Food
Some aquatic creatures love to eat brown algae for their survival and growth.
Introducing them into the tank can both eliminate the growth and prevent it from happening again.
Here are a few species to consider:
- Nerite Snails: These little guys are your best bet whether you’re trying to control brown algae in freshwater or saltwater aquariums. They won’t hurt the ecosystem and live plants while gobbling up silica in great amounts. They’ll clear the glass, substrate, rocks, and decorations of the brown enemy. Nerite snails can’t reproduce in freshwater, so you won’t have to worry about them infesting your tank in large numbers.
- Amano Shrimp: Amano shrimp are famous algae grazers. They’ll consume brown algae, hair algae, and other algae species happily. Much like Nerite snails, they won’t multiply in freshwater. Their only problem is that they won’t clean the glass, so you have to do that part yourself.
- Trochus Snails: The Trochus snail is an excellent addition to a marine tank’s cleanup crew. They’ll eat silica from all surfaces, and they’re also reef-safe.
- Mexican Turbo Snail: The Mexican Turbo snail will clean the algae off all the surfaces, including live rock, in a saltwater aquarium.
- Others: From the suckermouth family, the Bristlenose Plecos and Otoclinus Catfish will also eat brown algae.
What Is Silicate and Where Does It Come From?
Silicates are significant components of the earth’s crust, forming rocks and other materials.
A silicate molecule is an anion consisting of oxygen and silicon atoms.
Silicate or silicic acid can leach into your aquarium from many sources.
Your tap water can contain these chemicals or compounds that consist of these elements and later break down.
Some substrates, mainly silica sand, can dissolve quickly and leach out silicates into the water.
Salt mixes and fish food can also contain silicates and release them into the water.
What Is Silica Algae?
Silica algae, brown algae, or gravel algae form when millions of diatoms interlock and accumulate.
Diatoms are tiny single-celled organisms that become visible when they grow and build big colonies.
Diatom cells are always present in both freshwater and saltwater aquariums.
Given the right conditions, these cells will start to multiply.
Identifying silica algae is as easy as looking at the water.
It’ll turn rusty brown, and you’ll see thin brown patches coating the aquarium glass and gravel.
The patches will soon cover the plants, rocks, and decoration, as well.
Brown algae commonly take over newly set up tanks.
Once the aquarium is cycled, and the nutrients are balanced, the silica will automatically disappear.
Diatom blooms can also occur in established tanks when the nutrients are out of balance.
You need to take action to control the growth before the algae overrun your tank.
When the diatoms die, they deplete the oxygen levels in the water.
They can also populate at the base of the corals.
When they start to grow upwards, they push the polyp away from the skeleton.
As a result, the corals will recede, disintegrate, get infected, and die.
The Relation Between Silicates and Silica Algae
Diatoms or silica algae aren’t really a type of brown algae.
However, many hobbyists call them brown algae because of their similarities.
They both consume organic waste such as phosphates and nitrates to grow.
They also need light to grow.
Their main difference is that diatoms consume silicate (SiO2) and silicic acid to build their tough outer cell walls.
Once the silicate levels rise in the tank, the diatom cells are the first to consume them and form “brown algae” in the shape of hard, filamentous, or slimy patches.
However, as the silica algae die and decompose, they release the silicate they’ve absorbed back into the water column.
That’s why you should reduce the amount of silicate and remove brown algae simultaneously.