Aquarium Sand vs Gravel: the Pros and Cons

Written by Randy Martin

While preparing to setup my new fish tank I had to decide between sand or gravel for my aquarium substrate. I researched all the pros and cons between the two.

So sand vs gravel? Some fish species prefer a sand substrate. Sand looks natural and beautiful. However, sand is more prone to clouding your water, it could damage filters, and there is a chance of toxic air chambers forming in the sand. Gravel requires a deeper cleaning typically with a gravel vacuum.

There are several factors to consider, such as how easy each are to setup, to clean, which species you are planning on keeping, and what equipment you need . You should be aware of these things before making your decision of which substrate to go with. 

Main differences of sand and gravel

Installing the substrate

To get a tank setup with gravel is pretty easy. You just need to do a basic rinse wash and inspection before placing it into your tank.

With sand it is a lot different. Since one of the main challenges with sand is keeping the cloudiness down in your water, you have to go through a lengthy process before-hand to help offset this.

You need to wash out and rinse your sand a lot before putting it into your tank. And I mean a lot.

Instead of just one rinsing, you would repeat the washing process like 10 times—Maybe more. You would rinse the sand over and over again until it looks clear and usable to you. In the aquarium any cloudiness will be a lot more noticeable, so make sure it’s clean looking.

But after that hard work, you do get rewarded with…

Beauty factor

When it comes to looks, a sand substrate is just much prettier in your aquarium. Almost anyone would agree that it simply looks more natural and polished.

Gravel can look great too, in my opinion depending on the coloring. If you have an earthy natural tone, or dark gravel; that is a sharp look also.

But it’s kind of hard to beat out sand.

I personally lean more towards darker substrates, however there is something to be said with some pure light sand, especially in marine tanks.

Cleaning the substrate

When it comes to cleaning your tank, water changes etc. I don’t think either one is all that difficult. They are just different. Gravel takes a little more to maintain.

Gravel: You have food particles and waste that fall down into the substrate, into all the gaps and cracks. This actually lends towards a cleaner looking tank, since all the waste isn’t sitting on top of the bottom floor in plain view. 

But it usually takes more work to get all of that cleaned out. You need a gravel vac to really dive into the substrate to suck up all that junk that is sitting down there wasting away and dirtying up your tank.

Sand: With sand substrate the waste just sits right there on top. This has some advantages since you can clearly see how dirty your tank is getting, and it will be hard to ignore. If you have bottom feeders and scavengers this will give them more opportunity to help you clean.

It could be pretty unsightly to see all that junk at all times in your tank. Though your tank shouldn’t go uncleaned for long enough for it to be a real issue.

When doing water changes you can essentially vacuum up the waste right off the bottom. You just hold your hose a few inches off the ground, wave it back and forth, or use your hand to create a little current, which will lift all the dirty stuff higher up into the water, and then you can easily suck it up.

With a little practice you can do water changes with barely sucking up any of the sand itself, whatever you do happen to collect you can usually add it back to the tank with no issue.

Air pockets in the sand

This is one of the main risks with using sand. If you have a shallow sand bank like only an inch, this is less of a concern. But thicker sand bottoms have the risk of forming small air pockets, where old food and waste could potentially get trapped into it. Over time they decay filling that air pocket up with toxic gas. Then when that pocket is burst, it releases all that toxic gases into the aquarium.

This is easily avoided though, if you are keeping your tank well maintained

You should also do raking. After you have cleaned the bottom floor of the sand during a water change for example, then use your fingers or an object to gently rake through the sand, this will break up any of the air pockets that may be forming.

Important: When raking the sand make sure you do it after you have cleaned the bottom, so you don’t chance burying waste.

Equipment consideration for your bottom fill

Like I said with gravel you really need a gravel vac to get in there for a deep cleaning. With sand a regular siphon hose is sufficient.

If you are using sand then there are some risks to be aware about with your filter.

Many people have had sand ruin their filters, often times going through several filters quickly. You need to be very cautious when stirring up any of the sand during a water change. If you are running a hang on the back filter (HOB), turn it off while doing a water change and let the sand settle before turning it back on.

Following that guidance alone will help protect your filter. Though dealing with fish can be a different matter, some fish get a little crazier than others. Cichlids for example can really beat up your substrate and cloud things up significantly. So a good idea when using a sand bottom is to install a pre-sponge filter on your filters intake. This will help reduce the sand from being picked up and damaging the impeller.

You could also use a mechanical filter in a sand setup to safely decloud the water.

Lot’s of fishkeepers have ran normal HOB sponge filters with sand and haven’t had any issues, so it is doable. Of course it depends on your setup, fish, the type of sand etc.

What species are best for sand

Generally most bottom dwellers enjoy sand. Corys, Kuhli Loches, Plecos, etc. can go with either fine gravel or sand, but dwarf species such as dwarf loaches do need sand. Some sand is rougher than others, like the pool filter sand that is commonly used, so keep that in mind when placing fish like the corys who might be sensitive to that.

Shrimp almost require sand. They can get by in gravel and often do in many tanks. But they would be happiest in a nice soft sand bed to hunt in.

Pretty much every saltwater or reef tank is going to have sand, so it goes without saying that most marine species would prefer the sand.

What is the cost difference between sand and gravel

The cost varies depending on size, quality, color. When you are buying the substrate from pet stores and local fish shops, you should expect to pay more. And the price is comparable between these two at specialty stores.

The sand surprisingly enough could be a lot cheaper, since you can find cheap substitutes at local hardware stores. Blasting sand is something commonly used with many aquarium hobbyist. You can get away with a 50lb bag for extremely cheap.

The benefit from buying from pet stores or your local fish shop is you can find substrate that has beneficial additives for your water and plants. Also you can sometimes find a more quality color that in the end is going to look better in your tank.

Related Questions

Sand or gravel for Cichlids? Cichlids can be pretty destructive with any substrate. They may cause the water to become too cloudy by disturbing the sand, which could potentially harm your filtration system. It may be better to keep Cichlids in a tank with gravel.

Can I use an under gravel filter with sand? You shouldn’t combine sand with your under gravel filtration system. The sand will clog the system and potentially create dangerous air pockets that could fill up with toxic gas that could poison your fish.

Sand or gravel for planted aquarium? Plants can be planted in sand or gravel and do very well. Many plants work great in gravel, and you can find many that do very well in sand also. For example stem plants should do great in the sand as the root is mainly located on the stem itself.

Can you use sand in a tropical freshwater fish tank? Saltwater marine aquariums and Reef tanks for the most part use a sand substrate. Freshwater aquariums can also use sand as the substrate. Many freshwater species prefer sand—especially dwarf species and shrimp. 

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