The Pros & Cons of Sand Beds in a Marine Aquarium - Do You Really Need Sand?

We are continuing with our series on Starting your Own Simple Marine Aquarium today. In this article, we are going to be talking about the pros and cons of sand as a form of substrate. One thing you may have noticed about marine aquariums that differs, somewhat, from freshwater. Is the prevalence of tanks that don’t feature any kind of substrate.

Naturally, the most likely venue where you will spot aquariums like this is in your local fish shop. But plenty of marine fish tank owners choose to completely forgo substrate altogether. Opting for a bare bottom that they will then place their rocks directly onto.

This begs the question, why do people choose to do this? Well, some people simply prefer the way a bare bottom looks. People who need a lot of flow prefer bare bottom to avoid sand being kicked up into the water column. Some see it as cleaner and easier to maintain. Others like the extra floor space it affords for adding coral and rocks.

The Real Reason People Avoid Sand

Let’s be real for a second, here. We all have access to Reddit and marine aquarium specific forums. We can all read people’s genuine opinions on this subject. If you were to look deep enough into this and find answers for why people avoid sand. You would quickly come to one excuse above all the others. Maintenance.

The main reason people avoid it is that sand comes with a few problems that can make upkeep a bit more difficult. Sand needs vacuuming, sand needs stirring up, sand can contribute to nutrient problems, sand provides a surface area for algae to grow on. In short, sand gets dirty and it takes extra work to look after. Making maintenance even more of a pain than it already is

I am all too aware of this. I have sand in all of my tanks. Not a single one is bare bottom. The truth of the matter is, maintaining them takes extra work. I have to devote time to keeping detritus off the sand. I have to be sure to stir it up when cleaning. Vacuuming it can be a pain and that’s without even going into the subject of when a snail decides to dig itself a grave somewhere out of sight and out of mind.

There are days when I wish I had avoided sand beds because I simply can’t be bothered with the extra work. Lazy, I know, but true. Everyone who owns marine aquariums will have days like this. I know, however, that if I didn’t have sand I would be complaining about the problems caused by the absence of it.

With that being said, there are a bunch of positive benefits that will help your aquarium in the short term and, eventually, contribute to a healthier eco-system in the long term. Let’s take a look at both the pros and cons of having a sand bed in your marine aquarium.

A Sand Bed In You Aquarium – The Pros

• It Looks Better

Let’s start with the superficial. Some people will disagree but if you want that “true to life” reef look, sand is the way to go. It looks better, especially when the flow in your tank cuts through it to create a natural, bottom of the ocean, look.

• It Can Help With Cycling

If you opt for a sand bed in your aquarium and decide to purchase Live Sand, you can greatly speed up your cycling process. When we start a new aquarium, before we add fish, we need bacteria present that can transform ammonia, produced by the poop and rotting food in your tank, into a slightly less harmful compound called Nitrite. These nitrites will then be transformed, by a different type of bacteria, into the even less harmful compound Nitrates. This process is known as the Nitrogen Cycle.

We refer to the bacteria, in your aquarium, that accomplish this task as your Biological Filter. Live Sand comes packed with beneficial bacteria that will begin this nitrifying process straight away.

Cutting a big chunk of time out of how long it takes to get your aquarium up and running and making your aquarium’s ecosystem more diverse. We have already put together an article on Live Sand so check that out for more information.

• Supports Greater Biodiversity

Sand will greatly increase the potential for biodiversity in your aquarium as well as improving your biological filtration system. The added surface area supports a more diverse range of bacteria. Certain beneficial creatures hide and breed inside the sand; algae eating copepods, for example. Sand enables the ownership of certain snails that use the sand as a home in the daytime. And sand affords you the opportunity to cultivate a much more stable microbiome to support your tank in the future.

• Opens The Door to More Residents

Sand is essential for certain aquarium residents. With a decent sand bed, you can own things like Pistol Shrimp, certain snails, sand filtering Gobies, star fish, and much more. Quite a few creatures are completely off the table without sand and others won’t thrive without it. Plenty of your residents will appreciate the opportunity to hide in the sand, as well.

• Increases Long Term Stability

That extra surface area for bacteria will lead to greater biodiversity. This biodiversity will enable your aquarium to recover better from nutrient swings and will allow you to manage a larger fish population with less problems. Sand is made from Aragonite which is, basically, the broken down skeletons of dead coral. Aragonite is calcium rich and, as time goes on, this calcium will be released into the water. Helping to stabilise the PH levels of your water and creating an environment more accommodating to certain coral.

• A Surface Area For Algae Growth

This sounds like a bad thing but the second you own a tang, Foxface, or other algae eating fish you will appreciate it. Sand makes a great surface for growing algae. It is right under the lights and algae grows quickly on it. Your fish will be very grateful for this and will happily graze on it.

• Potential For Nitrate Reduction

This only comes with deep sand beds (DSBs) that are over 4 inches in depth but can be a great option for anyone looking for a low maintenance marine aquarium. A deep sand bed allows for the growth of a certain type of anaerobic bacteria that will convert the nitrates in the water into nitrogen gas. Effectively lowering your nitrates significantly. DSBs take more maintenance, especially to prevent pockets of dangerous gases forming. But they are an interesting option when building your marine aquarium.

A Sand Bed In You Aquarium – The Cons

• It Needs More Maintenance

Everything in life has pros and cons, Sand is no exception. The most noteworthy concern is the added maintenance that comes with having a sand bed. You simply can’t throw your sand in and then completely forget about it. It needs an extra level of care.

You should be stirring your sand bed every water change. Get all that brown crud suspended in the water column and then syphon it out. You may also want to vacuum the surface of the sand with the aforementioned syphon. This takes a bit of care to avoid removing too much sand from the tank but is worth doing.

• It Can Harbour Nutrients

Sand is aragonite, just like your rocks. This means it can soak up phosphates in exactly the same way. It can also trap rotting food that will then become a hidden source of nitrates in your tank. Again, you need to stir it up every time you change your water. Make sure you get that rotting food and poop suspended. Phosphates can be removed using a product like Rowaphos or GFO but that is an article for another day.

• It Grows Algae

This also appeared in the pros and it is a pro if you have algae eating fish. The truth is, the sand is going to grow algae and look messy. When you first experience issues like cyanobacteria, dinos or diatoms, you will notice them on your sand before anywhere else.

With things like Cyano and diatoms, this will almost definitely happen during the ugly stage and you just have to suffer through it for a few weeks. With other problems, it can be far tougher to deal with. Regular water changes and maintenance of your sand are essential to avoiding this.

• It Blows Around

This might be the biggest con. Sand gets everywhere, especially the finer grades. Sand can make creating decent flow in your aquarium a real nightmare. You can’t point a gyre down too far or a wavemaker into the base of the tank as you will soon be experiencing a massive sand storm.

If you haven’t been diligent with maintenance, this can create severe problems. As a bunch of rotten food and crap are kicked up into the water column. Thicker grades of sand help but it will always need some careful planning when it comes to directing flow.

Should You Have a Sand Bed?

This question is, ultimately, down to personal preference. If you prefer the way a bare bottom tank looks, skip the sand bed. Whatever you do, don’t skip the sand bed because you think bare bottom will be a lot easier to maintain. People who choose to forgo a sand bed, for this reason, usually end up disappointed.

Detritus will still accumulate all over the bottom of your tank and you may find it needs more frequent maintenance than a tank with sand. After all, there is nothing worse than fish crap staring at you on a panel of shiny glass. You will still need to blow it off or it will simply look nasty.

Sand beds offer a ton of benefits and you may miss those benefits in the long run. They look a lot more authentic, as well. Ultimately, it is down to personal preference but, if you want that proper reef look and you want a better environment for your critters. Go with a sand bed and prepare to do some extra maintenance. It will be worth it in the long run.

Which Sand Should I Start With?

We are going to go into this in its own article but there are a fair few options available to you. A simple search on Amazon will throw up a whole bunch of different types of sand. I am building this site with reefers in the UK in mind as you guys in the USA have tons of resources, unlike us. So, with that in mind, I will restrict my suggestions to what is available here.

You could choose to start with live sand to give your tank’s bacterial microbiome a real boost. As mentioned earlier, Live Sand comes packed with beneficial bacteria that will get to work, straight away, consuming ammonia. Jump starting your system. These companies boast that it is instantly cycling, a claim we dispute in our article on Live Sand – Can It Instantly Cycle Your Aquarium. But the bacteria present will help your early marine aquarium ownership tremendously.

Carib Sea are very well established and I have always been happy with every bag of sand I have bought from them. They have different grades of sand, different colours, and a range of sizes. The truth of the matter is, however, that live sand is a premium option. It is very expensive; over double the price of equivalent dry sand.

With this in mind, if you want to save money you probably want to be starting your aquarium with dry sand. Large, 25KG, bags can be purchased at online, UK, retailers for around £30-40 which is pretty affordable. Smaller quantities can be purchased for even less.

We can use bottled bacteria to make the dry sand live. Essentially accomplishing the task of the much more expensive live sand. Take a look at our article on Dry Sand for an explanation on what it is as well as the pros and cons.

You can also check out this article on Dry Sand vs Live Sand, Which Should You Choose to help you make a more informed decision on how to start.

In Short

The choice to include sand in your marine aquarium is entirely down to personal preference. Sand does, however, come with some benefits like a more authentic reef look, added surface area for increased bacterial growth, hiding places for critters, breeding area for beneficial invertebrates and, even, the possibility to own specific sand dwelling creatures like snails, gobies and starfish.

The added maintenance is worthy of note as sand can become a resting place for detritus and rotting food, meaning it needs blowing off and stirring up every time you change water. It can also bind up phosphates, leeching them out into the water over time. But these negatives are heavily outweighed by the positives. Thanks for reading.