Thinking of using a sand substrate for your goldfish tank?


I use sand in all my goldfish tanks and LOVE it.

But not all sands are created equal.

Using the wrong brand of sand can actually create a nightmare of chronic cloudy water and clogged equipment!

Best Sand for Goldfish Aquariums

Pool filter sand is a popular option because it’s so cheap.


I do not recommend that stuff at all.


It’s super messy and clouds the water.

Plus, it’s too fine.

There are some problems I’ve found in my experience with using fine sand substrates.

Finer grain size causes the particles to get totally sucked up into the siphon while you are vacuuming the tank.

This is an annoyance when doing a small water change with a bucket (you can still set the bucket out to dry the sand and put it back in later) and a plumbing problem if you are doing a large water change with a Python or other cleaning kit.

You’ll find it difficult to turn the pump that attaches to the sink once it gets clogged with sand.

Another thing is it gets sucked up in your filters and pump intakes, which can hurt your equipment.

That’s why I recommend using coarse sand instead.

My favorites?

The first has to be Caribsea Super Naturals “Crystal River.”

My goldfish go CRAZY over foraging in this stuff, and cleaning it is the easiest of all the brands I’ve tried.

It won’t mess with your pH and is easy to clean and all natural.

The color is a great neutral shade as well.

As long as your suction isn’t too strong, the particles gently lift into the tube and fall back down – but the waste continues to get sucked up.

This allows me to push the tube all the way to the bottom of the tank and get just about every piece of crud!

Yay 🙂

A cleaner tank = healthier, happier fish.

And unlike with gravel:

You get the benefits of something for the fish to forage in and enjoy without the hazards of choking and debris buildup.


The other awesome sand I’ve been super impressed with lately is Seachem Flourite black sand.

The reason?

It’s a sand made of nutrient-rich clay – perfect for the planted goldfish tank.

Plus it looks super striking.

Yes, it can be a bit cloudy initially, but me and many other fishkeepers agree – it’s worth the initial hassle to get the long-term results of a flourishing aquarium.

You can actually eliminate the need for liquid fertilizer dosing!

Benefits for Goldfish

Sand has many benefits for goldfish.

  • Does not trap debris, requiring less maintenance
  • Provides natural sifting behavior stimulation for foraging goldfish
  • Prevents hydrogen sulfide pocket production
  • Allows plants to root (unless your goldfish dig them up)
  • Enhances appearance of the aquarium

The Cleanlier Option

If you’ve ever had gravel in your aquarium, you know firsthand how downright nasty that stuff can get.

It seems like you can clean for AGES and never get all the debris out!

Fishkeepers who switch to sand from gravel almost always heave a massive sigh of relief:

“It’s so much easier to keep clean!”

This is because the fine particle size prevents waste from settling down into cracks and pockets, where it would sit and pollutes the water until someone disturbs it.

And the best part?

The waste tends to gather in areas of the tank where the current circulates, making vacuuming up all that poop in one fell swoop as easy as falling off a log.

Natural Behavior Encouragement

Bare-bottom tanks are definitely the easiest to keep clean…

… But they deprive the fish of the delights they have in sifting through and picking at things at the bottom.

In captivity, goldfish will be happiest when they can do what they would do if they lived in their natural environment – a pond or slow-moving river.

This behavior comes so naturally to them and gets them moving around their habitat longer, meaning more exercise and stimulation.

Why not let them do what they love?

I think it’s always a good idea to think of different ways to enrich their behavior and mimic natural conditions, especially by providing foraging material for them to graze on throughout the day.

How Deep of Sand Should You Use in Your Tank?

This is a good question.

My recommendation in general is not to use more than 1/2″ of sand at the bottom.

This prevents hydrogen sulfide pockets from forming.

(Nasty toxic pockets that can harm or kill your goldfish.)

Yes, with goldfish a shallower substrate depth can be a bit annoying because they really like to dig.

And you might have to sweep the sand every week or so to cover up any bare spots they might create.

The current from your filter can also cause bare spots.

But this isn’t a big deal to me since I usually have my hands in the tank doing cleaning or maintenance each week.

I don’t think you need to worry about really stirring it up each week like some fishkeepers do – since it’s not a deep layer.  I certainly don’t go crazy with this.


All that aside, if you have some deep rooting plants in your tank such as Amazon Swords, you can probably get away with using more than 1/2″ because the roots help to aerate the substrate and prevent these pockets from forming.

(Interestingly enough, some aquarists use deep sand beds as a method of filtration. Here’s an interesting article about that if you’re interested.)

Some people also keep Malaysian Trumpet Snails to aerate when they use deeper substrates – not that I would do that since they seem to be dirty little creatures.

They are used to turn the sand over.

Either way, I hope that helps clarify things for you.

Thoughts on Different Kinds of Sands

I already touched on why I don’t use sand that’s too fine.

But there are some other kinds I steer clear of too:

Some can have weird dyes or polymer coatings that can leach into your water over time.

I try to stay away from these.

The coatings are added to prevent the sand from influencing the pH (not a problem if you use Caribsea’s Crystal River).


White sand is something I will never try again.

The poop and any little speck of debris on the bottom stands out like a sore thumb.

The glare is harsh and unnatural.

And if you have any problem with brown algae… you can forget about white sand for long.

Wrapping it Up

I hope you enjoyed this article.

Did you learn something useful?

Have you ever used sand for your goldfish tank?

I’d love to hear your experiences in the comments below.