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Why Is My Aquarium Sand Turning Brown? (Read This First!)

If you own an aquarium, possibly you have noticed the sand in the aquarium is turning all brown and quickly taking over the interior of the aquarium. 

In case you are not aware of the exact reason, seeing these brownish sands in your aquarium, you may wonder why it’s turning brown.

So to learn the reasons that are making your aquarium sand brown, go through the detailed explanations ahead.

Why Is My Aquarium Sand Turning Brown?

Aquarium sand turns brown because of brown algae which are formed of billions of small and almost invisible interlocked diatoms. And it happens if the aquarium water has excess silicates, nitrates, or phosphates, if the new sand substrate is added such as play or pool sand, and due to poor lighting. 

As there are quite some potential reasons that cause brown algae or brownish colored sand in aquariums, so here you will be guided through the detailed explanations of all root cause so that you can understand why exactly it happens.

Excessive Silicates:

Having excessive amounts of silicates in the aquarium water is the number one reason that causes brown algae which make the aquarium sand appear brown.

Silicates are known to be the diatom’s most preferred food, so they start to thrive and reproduce there fully which increases the diatoms. And millions of diatoms together create brown algae which cause brownish-looking aquarium sand.

The main sources of silicates are tap and well water, salt mixes for aquariums, live rocks. So if any of them are being used in an aquarium, it will increase silicates as well as brown algae.

High Nitrates:

A high amount of nitrates in the tank water can cause brown algae in fish tanks as brown algae prefer to feed on nitrates as well.

A high amount of nitrates begins to build up in aquarium water if the water is not changed frequently. Also, Fish waste, fish food, plant fertilizers, deteriorated plant matter, and tap water is the other main sources of high nitrates and is responsible for brown algae. 

Therefore, the sand turns brown due to brown algae.

High Phosphates:

When the level of phosphate highly increases in the aquarium, it can fuel up both the diatoms and the formation of brown algae which will make the aquarium sand seem brown.

In a fish tank, the most potential origins for phosphates are uneaten fish foods, decayed plants, and fish waste as when these break down, they leave phosphates.

Besides, tap water, dead algae, dead fish, and KH and pH buffers are other main sources.

Poor Lighting:

Poor lighting in the fish tank also can spur the growth of diatoms which incite a brown algae outbreak. It’s because brown algae live well in poor lighting.

New Sand Substrate:

When a new sand substrate is added to the pool water such as pool and plays sand, it can rise the silicates in the aquarium. Therefore, brown algae occur. 

Is Brown Algae In Aquarium Good Or Bad?

Brown algae in any aquarium, especially in a newly set up aquarium are neither considered so bad nor good.

Brown algae are considered not bad because brown algae don’t harm any fish in the fish tank, neither do they kill fish. Also, fishes don’t seem to be bothered because of brown algae.

Besides, the diatoms that form brown algae consume carbon dioxide and then discharge oxygen that boosts the level of dissolved oxygen in the aquarium. Also, many people stated that such pure oxygenated water is essential for fish tanks.

However, if the aquarium has aquatic plants or corals and brown algae are coating them, it’s really bad because the aquatic plants will lose their ability to photosynthesize appropriately, thence will get weaken and may die even. 

Moreover, brown algae will turn a beautiful aquarium into a ghastly mess.

Should I Leave Brown Algae In My Fish Tank?

Brown algae in aquariums, especially if it’s a newly set up aquarium are a very natural occurrence. 

So if you have set up a new fish tank and it’s having brown algae but the brown algae are under control, you can leave them in the fish tank, as a few weeks later they are supposed to go away.

Also, sometimes some fishes prefer eating these brown algae and that helps to clear the aquarium.

But if the growth of brown algae is seeming rambunctious and they aren’t clearing up by themselves or taking many months, don’t ever leave them in your fish tank. Instead, clean the brown algae fastly by yourself as it can make the fish tank a total mess.

What Causes Brown Algae In Aquariums?

A high level of silicates, nitrates, or phosphates encourages the development of diatoms, and later billions of diatoms together cause brown algae in aquariums. Also, if the lighting for an aquarium is too weak, it can cause brown algae in aquariums. 

Using silica sand, salt mix, or live sand can cause brown algae in aquariums too as they increase the level of silicates in aquariums.

How Do You Get Rid Of Brown Algae In Sand?

Cleaning brown algae in the sand can be a little tricky, so here are two methods that have been included for you to look at it while cleaning brown algae in the sand.

Clean Brown Algae By Using A Fish Net:

Brown algae are supposed to sit on the upper layer of aquarium sand, therefore, you can easily get rid of them by using a fishnet only.

So first, get your fishnet and very gently run the fishnet along with the aquarium sand’s surface. And then just scoop out the slime-like brown algae from the top layer of sand. You must keep repeating this easy process until you have cleaned as many brown algae as possible in the sand.

Clean Brown Algae In Sand By Using A Gravel Vacuum:

Get a gravel vacuum and wave it above the sand’s top surface to collect any fish poop. After that, nip the hose off so there’s a little suction. Then move the sand in a good manner using that gravel vacuum and loosen up brown algae in the sand. 

Thereafter, pick your gravel vacuum out of aquarium sand and release the hose to get as much as brown algae you can.

In case, the brown algae aren’t budging, you can tape a pointy item to the vacuum’s tip to help you separate brown algae in the sand so that the vacuum can suck it.

Repeat the method until you have completely removed all brown algae in the sand.

How To Prevent Brown Algae In Fish Tanks?

Even after you have successfully gotten rid of brown algae in your fish tank, it can come back. So go through the following step-by-step instructions to prevent brown algae from making a comeback.

Proper Filtration:

First of all, inspect the aquarium’s filter to be sure that it’s graded for the liter capacity of the fish tank.

Then, make sure that you are keeping the filter always clean and it’s working accurately. And if nitrates released from the deteriorated plant matter, fish waste, etc. are an issue, use a protein skimmer which will keep the water clear and prevent brown algae.

Water Movement:

Always keep the water in your fish tank moving so that diatoms can’t clump together to form brown algae and latch on the surface of the sand in the fish tank.

You can use a powerhead or current maker to keep water moving.

Use RO Water:

Tap water or well water has a higher amount of silicates in them which encourages diatoms to form brown algae. So to prevent it, you should stop using tap water or well water. And replace it with reverse osmosis (RO) water because the impurities are removed from this water.

However, bottles of RO water can add up extra cost, so you can cover it up by using a RO filter system.

Don’t Overfeed:

Never overfeed your fish, as uneaten foods release nitrates which encourage brown algae formation.

Avoid All Sources Of Silicates

You must avoid all sources of silicates in your fish tank. So check ingredients carefully before adding any new things to the fish tank. And don’t use live sand, silica sand, or salt mix in the fish tank.

What Eats Brown Algae In Saltwater Tanks?

Quite a lot of fishes and critters like to eat brown algae in saltwater tanks, and a shortlist of such eaters has been added below.

  • Tailspot Blenny
  • Sailfin Tang
  • Kole Tang
  • Trochus Snail
  • Emerald Crab
  • Nassarius Snail
  • Cerith Snail
  • Fox Face
  • Tuxedo Urchin
  • Dolabella Sea Hare
  • Quoyi Parrotfish

Final Thoughts

When the level of silicates, nitrates, or phosphate is very high or the aquarium is getting poor lighting, diatoms which are unicellular organisms occur. And then billions of diatoms form brown algae which sit on the top surface of aquarium sand and make it look that the sand is turning brown.